Microsoft SQL Server
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Microsoft SQL Server is a
relational database management system A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relatio ...
developed by
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...
. As a
database server A database server is a server which uses a database application that provides database services to other computer programs or to computers, as defined by the client–server model. Database management systems (DBMSs) frequently provide database-s ...
, it is a
software product Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...
with the primary function of storing and retrieving data as requested by other
software application Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...
s—which may run either on the same computer or on another computer across a network (including the Internet). Microsoft markets at least a dozen different editions of Microsoft SQL Server, aimed at different audiences and for workloads ranging from small single-machine applications to large Internet-facing applications with many
concurrent user In computer science, the number of concurrent users (sometimes abbreviated CCU) for a resource in a location, with the location being a computing network or a single computer, refers to the total number of people simultaneously accessing or using t ...
s.


History

The history of Microsoft SQL Server begins with the first Microsoft SQL Server product—SQL Server 1.0, a 16-bit server for the
OS/2 OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 ...
operating system in 1989—and extends to the current day. Its name is entirely descriptive, it being ''
server Server may refer to: Computing *Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients Role * Waiting staff, those who work at a restaurant or a bar attending customers and su ...
'' software that responds to queries in the '' SQL'' language.


Milestones

* MS SQL Server for OS/2 began as a project to port
Sybase SQL Server SAP ASE (Adaptive Server Enterprise), originally known as Sybase SQL Server, and also commonly known as Sybase DB or Sybase ASE, is a relational model database server developed by Sybase Corporation, which later became part of SAP AG. ASE was ...
onto OS/2 in 1989, by Sybase, Ashton-Tate, and
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...
. * SQL Server 4.2 for NT is released in 1993, marking the entry onto
Windows NT Windows NT is a proprietary graphical operating system produced by Microsoft, the first version of which was released on July 27, 1993. It is a processor-independent, multiprocessing and multi-user operating system. The first version of Win ...
. * SQL Server 6.0 is released in 1995, marking the end of collaboration with Sybase; Sybase would continue developing their own variant of ''SQL Server'', Sybase Adaptive Server Enterprise, independently of Microsoft. * SQL Server 7.0 is released in 1998, marking the conversion of the source code from C to C++. * SQL Server 2005, released in 2005, finishes the complete revision of the old Sybase code into Microsoft code. * SQL Server 2012, released in 2012, adds columnar in-memory storage aka xVelocity. * SQL Server 2017, released in 2017, adds Linux support for these Linux platforms:
Red Hat Enterprise Linux Red Hat Enterprise Linux (RHEL) is a commercial open-source Linux distribution developed by Red Hat for the commercial market. Red Hat Enterprise Linux is released in server versions for x86-64, Power ISA, ARM64, and IBM Z and a desktop version ...
, SUSE Linux Enterprise Server,
Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed mostly of free and open-source software. Ubuntu is officially released in three editions: '' Desktop'', ''Server'', and ''Core'' for Internet of things devices and robots. All ...
& Docker Engine. * SQL Server 2019, released in 2019, adds Big Data Clusters, enhancements to the "Intelligent Database", enhanced monitoring features, updated developer experience, and updates/enhancements for Linux based installations. * SQL Server 2022, released in 2022, adds improved analytics, disaster recovery (to Azure, natch) the "Purview" unified data governance and management service, and plumbing improvements that make the database faster and more resilient.


Currently

, the following versions are supported by Microsoft: * SQL Server 2008 (with ESU program until July 12, 2022, With Azure installed since that date) * SQL Server 2012 (Until July 12, 2022, with ESU program since that date) * SQL Server 2014 * SQL Server 2016 * SQL Server 2017 * SQL Server 2019 * SQL Server 2022 (Azure-enabled) From SQL Server 2016 onward, the product is supported on x64 processors only and must have 1.4 GHz processor as a minimum, 2.0 GHz or faster is recommended. The current version is Microsoft SQL Server 2019, released November 4, 2019. The RTM version is 15.0.2000.5.


Editions

Microsoft makes SQL Server available in multiple editions, with different feature sets and targeting different users. These editions are:


Mainstream editions

; Enterprise: SQL Server Enterprise Edition includes both the core database engine and add-on services, with a range of tools for creating and managing a SQL Server cluster. It can manage databases as large as 524
petabyte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...
s and address 12
terabyte The byte is a units of information, unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character (computing), character of text in a computer and for this ...
s of memory and supports 640 logical processors (CPU cores). ; Standard: SQL Server Standard edition includes the core database engine, along with the stand-alone services. It differs from Enterprise edition in that it supports fewer active instances (number of nodes in a cluster) and does not include some high-availability functions such as hot-add memory (allowing memory to be added while the server is still running), and parallel indexes. ; Web: SQL Server Web Edition is a low- TCO option for Web hosting. ; Business intelligence: Introduced in SQL Server 2012 and focusing on Self Service and Corporate Business Intelligence. It includes the Standard Edition capabilities and Business Intelligence tools:
Power Pivot Power Pivot, formerly known as PowerPivot (without spacing), is a feature of Microsoft Excel, a computer software spreadsheet. It is available as an add-in in Excel 2010, 2013 in separate downloads, and as an add-in included with the Excel 2016 ...
, Power View, the BI Semantic Model, Master Data Services, Data Quality Services and xVelocity in-memory analytics. ; Workgroup: SQL Server Workgroup Edition includes the core database functionality but does not include the additional services. Note that this edition has been retired in SQL Server 2012. ; Express:
SQL Server Express Microsoft SQL Server Express is a version of Microsoft's SQL Server relational database management system that is free to download, distribute and use. It comprises a database specifically targeted for embedded and smaller-scale applications. Th ...
Edition is a scaled down, free edition of SQL Server, which includes the core database engine. While there are no limitations on the number of databases or users supported, it is limited to using one processor, 1 GB memory and 10 GB database files (4 GB database files prior to SQL Server Express 2008 R2). It is intended as a replacement for
MSDE Microsoft SQL Server Data Engine (MSDE, also Microsoft Data Engine or Microsoft Desktop Engine) is a relational database management system developed by Microsoft. It is a scaled-down version of Microsoft SQL Server 7.0 or 2000 which is free for n ...
. Two additional editions provide a superset of features not in the original Express Edition. The first is ''SQL Server Express with Tools'', which includes
SQL Server Management Studio Microsoft SQL Server Management Studio (SSMS) is a software application developed by Microsoft that is used for configuring, managing, and administering all components within Microsoft SQL Server. First launched with Microsoft SQL Server 2005, ...
Basic. ''SQL Server Express with Advanced Services'' adds full-text search capability and reporting services.


Specialized editions

; Azure:
Microsoft Azure SQL Database Microsoft Azure SQL Database (formerly SQL Azure, SQL Server Data Services, SQL Services, and Windows Azure SQL Database) is a managed cloud database ( PaaS) provided as part of Microsoft Azure. A cloud database is a database that runs on a clou ...
is the
cloud-based Cloud computing is the on-demand availability of computer system resources, especially data storage (cloud storage) and computing power, without direct active management by the user. Large clouds often have functions distributed over mult ...
version of Microsoft SQL Server, presented as a
platform as a service Platform as a service (PaaS) or application platform as a service (aPaaS) or platform-based service is a category of cloud computing services that allows customers to provision, instantiate, run, and manage a modular bundle comprising a computin ...
offering on
Microsoft Azure Microsoft Azure, often referred to as Azure ( , ), is a cloud computing platform operated by Microsoft for application management via around the world-distributed data centers. Microsoft Azure has multiple capabilities such as software as a ...
. ; Azure MPP: Azure SQL Data Warehouse is the
cloud-based Cloud computing is the on-demand availability of computer system resources, especially data storage (cloud storage) and computing power, without direct active management by the user. Large clouds often have functions distributed over mult ...
version of Microsoft SQL Server in a
MPP MPP or M.P.P. may refer to: * Marginal physical product * Master of Public Policy, an academic degree * Member of Provincial Parliament (Ontario), Canada * Member of Provincial Parliament (Western Cape), South Africa * ''Merriweather Post Pavilio ...
(massively parallel processing) architecture for analytics workloads, presented as a
platform as a service Platform as a service (PaaS) or application platform as a service (aPaaS) or platform-based service is a category of cloud computing services that allows customers to provision, instantiate, run, and manage a modular bundle comprising a computin ...
offering on
Microsoft Azure Microsoft Azure, often referred to as Azure ( , ), is a cloud computing platform operated by Microsoft for application management via around the world-distributed data centers. Microsoft Azure has multiple capabilities such as software as a ...
. ; Compact (SQL CE): The compact edition is an embedded database engine. Unlike the other editions of SQL Server, the SQL CE engine is based on SQL Mobile (initially designed for use with hand-held devices) and does not share the same binaries. Due to its small size (1 MB DLL footprint), it has a markedly reduced feature set compared to the other editions. For example, it supports a subset of the standard data types, does not support stored procedures or Views or multiple-statement batches (among other limitations). It is limited to 4 GB maximum database size and cannot be run as a Windows service, Compact Edition must be hosted by the application using it. The 3.5 version includes support for ADO.NET Synchronization Services. SQL CE does not support ODBC connectivity, unlike SQL Server proper. ; Developer:SQL Server Developer Edition includes the same features as SQL Server Enterprise Edition, but is limited by the license to be only used as a development and test system, and not as production server. Starting early 2016, Microsoft made this edition free of charge to the public. ; Embedded (SSEE): SQL Server 2005 Embedded Edition is a specially configured named instance of the SQL Server Express database engine which can be accessed only by certain Windows Services. ; Evaluation: SQL Server Evaluation Edition, also known as the ''Trial Edition'', has all the features of the Enterprise Edition, but is limited to 180 days, after which the tools will continue to run, but the server services will stop. ; Fast Track: SQL Server Fast Track is specifically for enterprise-scale data warehousing storage and business intelligence processing, and runs on reference-architecture hardware that is optimized for Fast Track. ; LocalDB: Introduced in SQL Server Express 2012, LocalDB is a minimal, on-demand, version of SQL Server that is designed for application developers. It can also be used as an embedded database. ;Analytics Platform System (APS): Formerly Parallel Data Warehouse (PDW) A
massively parallel processing Massively parallel is the term for using a large number of computer processors (or separate computers) to simultaneously perform a set of coordinated computations in parallel. GPUs are massively parallel architecture with tens of thousands of t ...
(MPP) SQL Server appliance optimized for large-scale
data warehousing In computing, a data warehouse (DW or DWH), also known as an enterprise data warehouse (EDW), is a system used for reporting and data analysis and is considered a core component of business intelligence. DWs are central repositories of integra ...
such as hundreds of terabytes. ;Datawarehouse Appliance Edition: Pre-installed and configured as part of an appliance in partnership with Dell & HP base on the Fast Track architecture. This edition does not include SQL Server Integration Services, Analysis Services, or Reporting Services.sqlcmd


Discontinued editions

; Microsoft Data Engine: Version 1.0 is based on SQL Server version 7.0. Afterwards, it was replaced by Microsoft SQL Server Data Engine. ; Microsoft SQL Server Data Engine: Also called Desktop Engine, Desktop Edition, it is based on SQL Server 2000. Intended for use as an application component, it did not include GUI management tools. Later, Microsoft also made available a web admin tool. Included with some versions of
Microsoft Access Microsoft Access is a database management system (DBMS) from Microsoft that combines the relational Access Database Engine (ACE) with a graphical user interface and software-development tools (not to be confused with the old Microsoft Access ...
, Microsoft development tools, and other editions of SQL Server. After SQL Server 2000, it was replaced by SQL Server 2005 Express Edition. ;Personal Edition: SQL Server 2000. Had workload or connection limits like MSDE, but no database size limit. Includes standard management tools. Intended for use as a mobile / disconnected proxy, licensed for use with SQL Server 2000 Standard edition. Similar to Standard Edition in SQL Server 2000, but Full-Text Search not working in Windows 98, transactional replication limited to subscriber. ;Datacenter: SQL Server 2008 R2 Datacenter is a full-featured edition of SQL Server and is designed for datacenters that need high levels of application support and scalability. It supports 256 logical processors and virtually unlimited memory and comes with StreamInsight Premium edition. The Datacenter edition has been retired in SQL Server 2012; all of its features are available in SQL Server 2012 Enterprise Edition. ;
Windows CE Windows Embedded Compact, formerly Windows Embedded CE, Windows Powered and Windows CE, is an operating system subfamily developed by Microsoft as part of its Windows Embedded family of products. Unlike Windows Embedded Standard, which is base ...
Edition: Introduced in SQL Server 2000, and was replaced by SQL Server 2005 Mobile Edition. ;SQL Server 2005 Mobile Edition: Replaced by SQL Server 2005 Compact Edition after 1 release. ;SQL Server 2005 Compact Edition: Replaced by
SQL Server Compact Microsoft SQL Server Compact (EOL, See SQL Express) (SQL CE) is a compact relational database produced by Microsoft for applications that run on mobile devices and desktops. Prior to the introduction of the desktop platform, it was known as ''SQL Se ...
3.5 after 1 release.


Supplemental packages

Tools published Microsoft include: *SQL Server 2000: :* Samples:SQL Server 2000 - Downloads
/ref> Northwind and pubs Sample Databases, Updated Samples for SQL Server 2000. :* Tools: Stress Testing and Performance Analysis tools (Read80Trace and OSTRESS), PSSDIAG Data Collection Utility, Notification services (up to service pack 1), Security Tools, Best Practices Analyzer 1.0, Reporting Services (up to Service Pack 2), Reporting Services Report Packs, SQL Server 2000 Driver for JDBC (up to service pack 3), SQLXML 3.0 (up to service pack 3). :* Documentation:SQL Server 2000 Product Documentation
/ref> SQL Server 2000 Books Online, SQL Server 2000 System Table Map, Resource Kit, SQL Server 2000 — Getting Started Guide.


Architecture

The protocol layer implements the external interface to SQL Server. All operations that can be invoked on SQL Server are communicated to it via a Microsoft-defined format, called
Tabular Data Stream Tabular Data Stream (TDS) is an application layer Protocol (computing), protocol used to transfer data between a database server and a client. It was initially designed and developed by Sybase Inc. for their Sybase SQL Server relational database eng ...
(TDS). TDS is an application layer protocol, used to transfer data between a database server and a client. Initially designed and developed by Sybase Inc. for their
Sybase SQL Server SAP ASE (Adaptive Server Enterprise), originally known as Sybase SQL Server, and also commonly known as Sybase DB or Sybase ASE, is a relational model database server developed by Sybase Corporation, which later became part of SAP AG. ASE was ...
relational database engine in 1984, and later by Microsoft in Microsoft SQL Server, TDS packets can be encased in other physical transport dependent protocols, including
TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
,
named pipe In computing, a named pipe (also known as a FIFO for its behavior) is an extension to the traditional pipe concept on Unix and Unix-like systems, and is one of the methods of inter-process communication (IPC). The concept is also found in OS/2 and ...
s, and
shared memory In computer science, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Shared memory is an efficient means of passing data between progr ...
. Consequently, access to SQL Server is available over these protocols. In addition, the SQL Server API is also exposed over web services.


Data storage

Data storage is a
database In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases sp ...
, which is a collection of tables with typed columns. SQL Server supports different data types, including
primitive type In computer science, primitive data types are a set of basic data types from which all other data types are constructed. Specifically it often refers to the limited set of data representations in use by a particular processor, which all compiled p ...
s such as ''Integer'', ''Float'', ''Decimal'', ''Char'' (including character strings), ''Varchar'' (variable length character strings), binary (for unstructured blobs of data), ''Text'' (for textual data) among others. The
rounding Rounding means replacing a number with an approximate value that has a shorter, simpler, or more explicit representation. For example, replacing $ with $, the fraction 312/937 with 1/3, or the expression with . Rounding is often done to ob ...
of floats to integers uses either Symmetric Arithmetic Rounding or Symmetric Round Down (''fix'') depending on arguments: SELECT Round(2.5, 0) gives 3. Microsoft SQL Server also allows user-defined composite types (UDTs) to be defined and used. It also makes server statistics available as virtual tables and views (called Dynamic Management Views or DMVs). In addition to tables, a database can also contain other objects including
views A view is a sight or prospect or the ability to see or be seen from a particular place. View, views or Views may also refer to: Common meanings * View (Buddhism), a charged interpretation of experience which intensely shapes and affects thou ...
, stored procedures,
indexes Index (or its plural form indices) may refer to: Arts, entertainment, and media Fictional entities * Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index'' * The Index, an item on a Halo megastru ...
and constraints, along with a transaction log. A SQL Server database can contain a maximum of 231 objects, and can span multiple OS-level files with a maximum file size of 260 bytes (1 exabyte). The data in the database are stored in primary data files with an extension .mdf. Secondary data files, identified with a .ndf extension, are used to allow the data of a single database to be spread across more than one file, and optionally across more than one file system. Log files are identified with the .ldf extension. Storage space allocated to a database is divided into sequentially numbered ''pages'', each 8 KB in size. A ''page'' is the basic unit of I/O for SQL Server operations. A page is marked with a 96-byte header which stores metadata about the page including the page number, page type, free space on the page and the ID of the object that owns it. The page type defines the data contained in the page. This data includes: data stored in the database, an index, an allocation map, which holds information about how pages are allocated to tables and indexes; and a change map which holds information about the changes made to other pages since last backup or logging, or contain large data types such as image or text. While a page is the basic unit of an I/O operation, space is actually managed in terms of an ''extent'' which consists of 8 pages. A database object can either span all 8 pages in an extent ("uniform extent") or share an extent with up to 7 more objects ("mixed extent"). A row in a database table cannot span more than one page, so is limited to 8 KB in size. However, if the data exceeds 8 KB and the row contains ''varchar'' or ''varbinary'' data, the data in those columns are moved to a new page (or possibly a sequence of pages, called an ''allocation unit'') and replaced with a pointer to the data. For physical storage of a table, its rows are divided into a series of partitions (numbered 1 to n). The partition size is user defined; by default all rows are in a single partition. A table is split into multiple partitions in order to spread a database over a
computer cluster A computer cluster is a set of computers that work together so that they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software. The comp ...
. Rows in each partition are stored in either
B-tree In computer science, a B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree generalizes the binary search tree, allowing for ...
or heap structure. If the table has an associated, clustered
index Index (or its plural form indices) may refer to: Arts, entertainment, and media Fictional entities * Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index'' * The Index, an item on a Halo megastru ...
to allow fast retrieval of rows, the rows are stored in-order according to their index values, with a B-tree providing the index. The data is in the leaf node of the leaves, and other nodes storing the index values for the leaf data reachable from the respective nodes. If the index is non-clustered, the rows are not sorted according to the index keys. An indexed view has the same storage structure as an indexed table. A table without a clustered index is stored in an unordered heap structure. However, the table may have non-clustered indices to allow fast retrieval of rows. In some situations the heap structure has performance advantages over the clustered structure. Both heaps and B-trees can span multiple allocation units.


Buffer management

SQL Server
buffer Buffer may refer to: Science * Buffer gas, an inert or nonflammable gas * Buffer solution, a solution used to prevent changes in pH * Buffering agent, the weak acid or base in a buffer solution * Lysis buffer, in cell biology * Metal ion buffer * ...
s pages in RAM to minimize disk I/O. Any 8 KB page can be buffered in-memory, and the set of all pages currently buffered is called the buffer cache. The amount of memory available to SQL Server decides how many pages will be cached in memory. The buffer cache is managed by the ''Buffer Manager''. Either reading from or writing to any page copies it to the buffer cache. Subsequent reads or writes are redirected to the in-memory copy, rather than the on-disc version. The page is updated on the disc by the Buffer Manager only if the in-memory cache has not been referenced for some time. While writing pages back to disc,
asynchronous I/O In computer science, asynchronous I/O (also non-sequential I/O) is a form of input/output processing that permits other processing to continue before the transmission has finished. A name used for asynchronous I/O in the Windows API is overlappe ...
is used whereby the I/O operation is done in a background thread so that other operations do not have to wait for the I/O operation to complete. Each page is written along with its
checksum A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify data ...
when it is written. When reading the page back, its checksum is computed again and matched with the stored version to ensure the page has not been damaged or tampered with in the meantime.


Concurrency and locking

SQL Server allows multiple clients to use the same database concurrently. As such, it needs to control concurrent access to shared data, to ensure data integrity—when multiple clients update the same data, or clients attempt to read data that is in the process of being changed by another client. SQL Server provides two modes of concurrency control: pessimistic concurrency and optimistic concurrency. When pessimistic concurrency control is being used, SQL Server controls concurrent access by using locks. Locks can be either shared or exclusive. Exclusive lock grants the user exclusive access to the data—no other user can access the data as long as the lock is held. Shared locks are used when some data is being read—multiple users can read from data locked with a shared lock, but not acquire an exclusive lock. The latter would have to wait for all shared locks to be released. Locks can be applied on different levels of granularity—on entire tables, pages, or even on a per-row basis on tables. For indexes, it can either be on the entire index or on index leaves. The level of granularity to be used is defined on a per-database basis by the database administrator. While a fine-grained locking system allows more users to use the table or index simultaneously, it requires more resources, so it does not automatically yield higher performance. SQL Server also includes two more lightweight
mutual exclusion In computer science, mutual exclusion is a property of concurrency control, which is instituted for the purpose of preventing race conditions. It is the requirement that one thread of execution never enters a critical section while a concurrent ...
solutions—latches and spinlocks—which are less robust than locks but are less resource intensive. SQL Server uses them for DMVs and other resources that are usually not busy. SQL Server also monitors all worker threads that acquire locks to ensure that they do not end up in
deadlock In concurrent computing, deadlock is any situation in which no member of some group of entities can proceed because each waits for another member, including itself, to take action, such as sending a message or, more commonly, releasing a loc ...
s—in case they do, SQL Server takes remedial measures, which in many cases are to kill one of the threads entangled in a deadlock and roll back the transaction it started. To implement locking, SQL Server contains the ''Lock Manager''. The Lock Manager maintains an in-memory table that manages the database objects and locks, if any, on them along with other metadata about the lock. Access to any shared object is mediated by the lock manager, which either grants access to the resource or blocks it. SQL Server also provides the optimistic concurrency control mechanism, which is similar to the
multiversion concurrency control Multiversion concurrency control (MCC or MVCC), is a concurrency control method commonly used by database management systems to provide concurrent access to the database and in programming languages to implement transactional memory. Description ...
used in other databases. The mechanism allows a new version of a row to be created whenever the row is updated, as opposed to overwriting the row, i.e., a row is additionally identified by the ID of the transaction that created the version of the row. Both the old as well as the new versions of the row are stored and maintained, though the old versions are moved out of the database into a system database identified as Tempdb. When a row is in the process of being updated, any other requests are not blocked (unlike locking) but are executed on the older version of the row. If the other request is an update statement, it will result in two different versions of the rows—both of them will be stored by the database, identified by their respective transaction IDs.


Data retrieval and programmability

The main mode of retrieving data from a SQL Server database is querying for it. The query is expressed using a variant of SQL called
T-SQL Transact-SQL (T-SQL) is Microsoft's and Sybase's proprietary extension to the SQL (Structured Query Language) used to interact with relational databases. T-SQL expands on the SQL standard to include procedural programming, local variables, var ...
, a dialect Microsoft SQL Server shares with
Sybase SQL Server SAP ASE (Adaptive Server Enterprise), originally known as Sybase SQL Server, and also commonly known as Sybase DB or Sybase ASE, is a relational model database server developed by Sybase Corporation, which later became part of SAP AG. ASE was ...
due to its legacy. The query declaratively specifies what is to be retrieved. It is processed by the query processor, which figures out the sequence of steps that will be necessary to retrieve the requested data. The sequence of actions necessary to execute a query is called a query plan. There might be multiple ways to process the same query. For example, for a query that contains a
join Join may refer to: * Join (law), to include additional counts or additional defendants on an indictment *In mathematics: ** Join (mathematics), a least upper bound of sets orders in lattice theory ** Join (topology), an operation combining two top ...
statement and a select statement, executing join on both the tables and then executing select on the results would give the same result as selecting from each table and then executing the join, but result in different execution plans. In such case, SQL Server chooses the plan that is expected to yield the results in the shortest possible time. This is called
query optimization Query optimization is a feature of many relational database management systems and other databases such as NoSQL and graph databases. The query optimizer attempts to determine the most efficient way to execute a given query by considering the p ...
and is performed by the query processor itself. SQL Server includes a cost-based query optimizer which tries to optimize on the cost, in terms of the resources it will take to execute the query. Given a query, then the query optimizer looks at the
database schema The database schema is the structure of a database described in a formal language supported by the database management system (DBMS). The term "schema" refers to the organization of data as a blueprint of how the database is constructed (divide ...
, the database statistics and the system load at that time. It then decides which sequence to access the tables referred in the query, which sequence to execute the operations and what access method to be used to access the tables. For example, if the table has an associated index, whether the index should be used or not: if the index is on a column which is not unique for most of the columns (low "selectivity"), it might not be worthwhile to use the index to access the data. Finally, it decides whether to execute the query concurrently or not. While a concurrent execution is more costly in terms of total processor time, because the execution is actually split to different processors might mean it will execute faster. Once a query plan is generated for a query, it is temporarily cached. For further invocations of the same query, the cached plan is used. Unused plans are discarded after some time. SQL Server also allows stored procedures to be defined. Stored procedures are parameterized T-SQL queries, that are stored in the server itself (and not issued by the client application as is the case with general queries). Stored procedures can accept values sent by the client as input parameters, and send back results as output parameters. They can call defined functions, and other stored procedures, including the same stored procedure (up to a set number of times). They can be selectively provided access to. Unlike other queries, stored procedures have an associated name, which is used at runtime to resolve into the actual queries. Also because the code need not be sent from the client every time (as it can be accessed by name), it reduces network traffic and somewhat improves performance. Execution plans for stored procedures are also cached as necessary.


T-SQL

T-SQL (Transact-SQL) is Microsoft's proprietary
procedural language Procedural programming is a programming paradigm, derived from imperative programming, based on the concept of the ''procedure call''. Procedures (a type of routine or subroutine) simply contain a series of computational steps to be carried ...
extension for SQL Server. It provides REPL (Read-Eval-Print-Loop) instructions that extend standard SQL's instruction set for Data Manipulation ( DML) and Data Definition ( DDL) instructions, including SQL Server-specific settings, security and database statistics management. It exposes keywords for the operations that can be performed on SQL Server, including creating and altering database schemas, entering and editing data in the database as well as monitoring and managing the server itself. Client applications that consume data or manage the server will leverage SQL Server functionality by sending T-SQL queries and statements which are then processed by the server and results (or errors) returned to the client application. For this it exposes read-only tables from which server statistics can be read. Management functionality is exposed via system-defined stored procedures which can be invoked from T-SQL queries to perform the management operation. It is also possible to create linked Servers using T-SQL. Linked servers allow a single query to process operations performed on multiple servers.


SQL Server Native Client (a.k.a. SNAC)

SQL Server Native Client is the native client side data access
library A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vir ...
for Microsoft SQL Server, version 2005 onwards. It natively implements support for the SQL Server features including the
Tabular Data Stream Tabular Data Stream (TDS) is an application layer Protocol (computing), protocol used to transfer data between a database server and a client. It was initially designed and developed by Sybase Inc. for their Sybase SQL Server relational database eng ...
implementation, support for mirrored SQL Server databases, full support for all data types supported by SQL Server, asynchronous operations, query notifications,
encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...
support, as well as receiving multiple result sets in a single database session. SQL Server Native Client is used under the hood by SQL Server plug-ins for other data access technologies, including ADO or
OLE DB OLE DB (''Object Linking and Embedding, Database'', sometimes written as OLEDB or OLE-DB), an API designed by Microsoft, allows accessing data from a variety of sources in a uniform manner. The API provides a set of interfaces implemented using ...
. The SQL Server Native Client can also be directly used, bypassing the generic data access layers. On November 28, 2011, a preview release of the SQL Server
ODBC In computing, Open Database Connectivity (ODBC) is a standard application programming interface (API) for accessing database management systems (DBMS). The designers of ODBC aimed to make it independent of database systems and operating systems. An ...
driver for
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
was released.


SQL CLR

Microsoft SQL Server 2005 includes a component named
SQL CLR SQL CLR or SQLCLR ( SQL Common Language Runtime) is technology for hosting of the Microsoft .NET common language runtime engine within SQL Server. The SQLCLR allows managed code to be hosted by, and run in, the Microsoft SQL Server environment. T ...
("Common Language Runtime") via which it integrates with
.NET Framework The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...
. Unlike most other applications that use .NET Framework, SQL Server itself hosts the .NET Framework runtime, i.e., memory, threading and resource management requirements of .NET Framework are satisfied by SQLOS itself, rather than the underlying Windows operating system. SQLOS provides deadlock detection and resolution services for .NET code as well. With SQL CLR, stored procedures and
trigger Trigger may refer to: Notable animals and people ;Mononym * Trigger (horse), owned by cowboy star Roy Rogers ;Nickname * Trigger Alpert (1916–2013), American jazz bassist * "Trigger Mike" Coppola (1900–1966), American gangster ;Surname * Bru ...
s can be written in any managed
.NET language The domain name net is a generic top-level domain (gTLD) used in the Domain Name System of the Internet. The name is derived from the word ''network'', indicating it was originally intended for organizations involved in networking technologies ...
, including C# and
VB.NET Visual Basic, originally called Visual Basic .NET (VB.NET), is a multi-paradigm, object-oriented programming language, implemented on .NET, Mono, and the .NET Framework. Microsoft launched VB.NET in 2002 as the successor to its original Visua ...
.
Managed code Managed code is computer program code that requires and will execute only under the management of a Common Language Infrastructure (CLI); Virtual Execution System (VES); virtual machine, e.g. .NET, CoreFX, or .NET Framework; Common Language Runt ...
can also be used to define UDT's ( user defined types), which can persist in the database.
Managed code Managed code is computer program code that requires and will execute only under the management of a Common Language Infrastructure (CLI); Virtual Execution System (VES); virtual machine, e.g. .NET, CoreFX, or .NET Framework; Common Language Runt ...
is compiled to CLI assemblies and after being verified for
type safety In computer science, type safety and type soundness are the extent to which a programming language discourages or prevents type errors. Type safety is sometimes alternatively considered to be a property of facilities of a computer language; that is ...
, registered at the database. After that, they can be invoked like any other procedure. However, only a subset of the
Base Class Library The Standard Libraries is a set of libraries included in the Common Language Infrastructure (CLI) in order to encapsulate many common functions, such as file reading and writing, XML document manipulation, exception handling, application globa ...
is available, when running code under SQL CLR. Most APIs relating to
user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...
functionality are not available. When writing code for SQL CLR, data stored in SQL Server databases can be accessed using the ADO.NET
API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...
s like any other managed application that accesses SQL Server data. However, doing that creates a new database session, different from the one in which the code is executing. To avoid this, SQL Server provides some enhancements to the ADO.NET provider that allows the connection to be redirected to the same session which already hosts the running code. Such connections are called context connections and are set by setting context connection parameter to true in the connection string. SQL Server also provides several other enhancements to the ADO.NET API, including classes to work with tabular data or a single row of data as well as classes to work with internal metadata about the data stored in the database. It also provides access to the XML features in SQL Server, including
XQuery XQuery (XML Query) is a query and functional programming language that queries and transforms collections of structured and unstructured data, usually in the form of XML, text and with vendor-specific extensions for other data formats (JSON, bin ...
support. These enhancements are also available in T-SQL Procedures in consequence of the introduction of the new XML Datatype (query, value, nodes functions).


Services

SQL Server also includes an assortment of add-on services. While these are not essential for the operation of the database system, they provide value added services on top of the core database management system. These services either run as a part of some SQL Server component or out-of-process as
Windows Service In Windows NT operating systems, a Windows service is a computer program that operates in the background. It is similar in concept to a Unix daemon. A Windows service must conform to the interface rules and protocols of the Service Control Manager ...
and presents their own
API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...
to control and interact with them.


Machine Learning Services

The SQL Server Machine Learning services operates within the SQL server instance, allowing people to do machine learning and data analytics without having to send data across the network or be limited by the memory of their own computers. The services come with Microsoft's R and Python distributions that contain commonly used packages for data science, along with some proprietary packages (e.g.
revoscalepy revoscalepy is a machine learning package in Python created by Microsoft. It is available as part of Machine Learning Services in Microsoft SQL Server 2017 and Machine Learning Server 9.2.0 and later. The package contains functions for creating l ...
,
RevoScaleR RevoScaleR is a machine learning package in R created by Microsoft. It is available as part of Machine Learning Server, Microsoft R Client, and Machine Learning Services in Microsoft SQL Server 2016. The package contains functions for creating l ...
, microsoftml) that can be used to create machine models at scale. Analysts can either configure their client machine to connect to a remote SQL server and push the script executions to it, or they can run a R or Python scripts as an external script inside a T-SQL query. The trained machine learning model can be stored inside a database and used for scoring.


Service Broker

Used inside an instance, programming environment. For cross-instance applications, Service Broker communicates over
TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
and allows the different components to be synchronized, via exchange of messages. The Service Broker, which runs as a part of the database engine, provides a reliable messaging and message queuing platform for SQL Server applications. Service broker services consists of the following parts: * message types * contracts * queues * service programs * routes The message type defines the data format used for the message. This can be an XML object, plain text or binary data, as well as a
null Null may refer to: Science, technology, and mathematics Computing * Null (SQL) (or NULL), a special marker and keyword in SQL indicating that something has no value * Null character, the zero-valued ASCII character, also designated by , often use ...
message body for notifications. The contract defines which messages are used in an conversation between services and who can put messages in the queue. The queue acts as storage provider for the messages. They are internally implemented as tables by SQL Server, but don't support insert, update, or delete functionality. The service program receives and processes service broker messages. Usually the service program is implemented as stored procedure or
CLR CLR may refer to: * Calcium Lime Rust, a household cleaning-product * California Law Review, a publication by the UC Berkeley School of Law * Tube_bending, Centerline Radius, a term in the tubing industry used to describe the radius of a bend * Cen ...
application. Routes are network addresses where the service broker is located on the network. Also, service broker supports security features like network authentication (using
NTLM In a Windows network, NT (New Technology) LAN Manager (NTLM) is a suite of Microsoft security protocols intended to provide authentication, integrity, and confidentiality to users. NTLM is the successor to the authentication protocol in Microsoft L ...
, Kerberos, or authorization certificates), integrity checking, and message
encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...
.


Replication Services

SQL Server Replication Services are used by SQL Server to replicate and synchronize database objects, either in entirety or a subset of the objects present, across replication agents, which might be other database servers across the network, or database caches on the client side. Replication Services follows a publisher/subscriber model, i.e., the changes are sent out by one database server ("publisher") and are received by others ("subscribers"). SQL Server supports three different types of replication: ; Transaction replication: Each transaction made to the publisher database (master database) is synced out to subscribers, who update their databases with the transaction. Transactional replication synchronizes databases in near real time. ; Merge replication: Changes made at both the publisher and subscriber databases are tracked, and periodically the changes are synchronized bi-directionally between the publisher and the subscribers. If the same data has been modified differently in both the publisher and the subscriber databases, synchronization will result in a conflict which has to be resolved, either manually or by using pre-defined policies. rowguid needs to be configured on a column if merge replication is configured. ; Snapshot replication: Snapshot replication publishes a copy of the entire database (the then-snapshot of the data) and replicates out to the subscribers. Further changes to the snapshot are not tracked.


Analysis Services

SQL Server Analysis Services (SSAS) adds
OLAP Online analytical processing, or OLAP (), is an approach to answer multi-dimensional analytical (MDA) queries swiftly in computing. OLAP is part of the broader category of business intelligence, which also encompasses relational databases, repor ...
and data mining capabilities for SQL Server databases. The OLAP engine supports
MOLAP Online analytical processing, or OLAP (), is an approach to answer multi-dimensional analytical (MDA) queries swiftly in computing. OLAP is part of the broader category of business intelligence, which also encompasses relational databases, rep ...
,
ROLAP Online analytical processing, or OLAP (), is an approach to answer multi-dimensional analytical (MDA) queries swiftly in computing. OLAP is part of the broader category of business intelligence, which also encompasses relational databases, re ...
and
HOLAP Online analytical processing, or OLAP (), is an approach to answer multi-dimensional analytical (MDA) queries swiftly in computing. OLAP is part of the broader category of business intelligence, which also encompasses relational databases, repo ...
storage modes for data. Analysis Services supports the
XML for Analysis XML for Analysis (XMLA) is an industry standard for data access in analytical systems, such as online analytical processing (OLAP) and data mining. XMLA is based on other industry standards such as XML, SOAP and HTTP. XMLA is maintained by XMLA Cou ...
standard as the underlying communication protocol. The cube data can be accessed using MDX and LINQ queries. Data mining specific functionality is exposed via the DMX query language. Analysis Services includes various algorithms—
Decision trees A decision tree is a decision support tool that uses a tree-like model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. It is one way to display an algorithm that only contains condit ...
, clustering algorithm,
Naive Bayes In statistics, naive Bayes classifiers are a family of simple "Probabilistic classification, probabilistic classifiers" based on applying Bayes' theorem with strong (naive) statistical independence, independence assumptions between the features (s ...
algorithm, time series analysis, sequence clustering algorithm, linear and logistic regression analysis, and
neural network A neural network is a network or circuit of biological neurons, or, in a modern sense, an artificial neural network, composed of artificial neurons or nodes. Thus, a neural network is either a biological neural network, made up of biological ...
s—for use in data mining.


Reporting Services

SQL Server Reporting Services (SSRS) is a report generation environment for data gathered from SQL Server databases. It is administered via a
web interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fr ...
. Reporting services features a web services interface to support the development of custom reporting applications. Reports are created as RDL files. Reports can be designed using recent versions of
Microsoft Visual Studio Visual Studio is an integrated development environment (IDE) from Microsoft. It is used to develop computer programs including websites, web apps, web services and mobile apps. Visual Studio uses Microsoft software development platforms such a ...
(Visual Studio.NET 2003, 2005, and 2008) with Business Intelligence Development Studio, installed or with the included Report Builder. Once created, RDL files can be rendered in a variety of formats, including Excel,
PDF Portable Document Format (PDF), standardized as ISO 32000, is a file format developed by Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. ...
, CSV,
XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...
, BMP, EMF,
GIF The Graphics Interchange Format (GIF; or , see pronunciation) is a bitmap image format that was developed by a team at the online services provider CompuServe led by American computer scientist Steve Wilhite and released on 15 June 1987. ...
,
JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and imag ...
, PNG, and
TIFF Tag Image File Format, abbreviated TIFF or TIF, is an image file format for storing raster graphics images, popular among graphic artists, the publishing industry, and photographers. TIFF is widely supported by scanning, faxing, word processin ...
, and HTML Web Archive.


Notification Services

Originally introduced as a post-release add-on for SQL Server 2000, Notification Services was bundled as part of the Microsoft SQL Server platform for the first and only time with SQL Server 2005. SQL Server Notification Services is a mechanism for generating data-driven notifications, which are sent to Notification Services subscribers. A subscriber registers for a specific event or transaction (which is registered on the database server as a trigger); when the event occurs, Notification Services can use one of three methods to send a message to the subscriber informing about the occurrence of the event. These methods include SMTP, SOAP, or by writing to a file in the filesystem. Notification Services was discontinued by Microsoft with the release of SQL Server 2008 in August 2008, and is no longer an officially supported component of the SQL Server database platform.


Integration Services

SQL Server Integration Services (SSIS) provides ETL capabilities for SQL Server for
data import The import and export of data is the automated or semi-automated input and output of data sets between different software applications. It involves "translating" from the format used in one application into that used by another, where such translat ...
,
data integration Data integration involves combining data residing in different sources and providing users with a unified view of them. This process becomes significant in a variety of situations, which include both commercial (such as when two similar companies ...
and
data warehousing In computing, a data warehouse (DW or DWH), also known as an enterprise data warehouse (EDW), is a system used for reporting and data analysis and is considered a core component of business intelligence. DWs are central repositories of integra ...
needs. Integration Services includes GUI tools to build
workflow A workflow consists of an orchestrated and repeatable pattern of activity, enabled by the systematic organization of resources into processes that transform materials, provide services, or process information. It can be depicted as a sequence of ...
s such as extracting data from various sources, querying data, transforming data—including aggregation, de-duplication, de-/normalization and merging of data—and then exporting the transformed data into destination databases or files.


Full Text Search Service

SQL Server Full Text Search service is a specialized indexing and querying service for unstructured text stored in SQL Server databases. The full text search index can be created on any column with character based text data. It allows for words to be searched for in the text columns. While it can be performed with the SQL LIKE operator, using SQL Server Full Text Search service can be more efficient. Full allows for inexact matching of the source string, indicated by a ''Rank'' value which can range from 0 to 1000—a higher rank means a more accurate match. It also allows linguistic matching ("inflectional search"), i.e., linguistic variants of a word (such as a verb in a different tense) will also be a match for a given word (but with a lower rank than an exact match). Proximity searches are also supported, i.e., if the words searched for do not occur in the sequence they are specified in the query but are near each other, they are also considered a match. T-SQL exposes special operators that can be used to access the FTS capabilities. The Full Text Search engine is divided into two processes: the ''Filter Daemon'' process (msftefd.exe) and the ''Search'' process (msftesql.exe). These processes interact with the SQL Server. The Search process includes the indexer (that creates the full text indexes) and the full text query processor. The indexer scans through text columns in the database. It can also index through binary columns, and use
iFilter An IFilter is a plugin that allows Microsoft's search engines to index various file formats (as documents, email attachments, database records, audio metadata etc.) so that they become searchable. Without an appropriate IFilter, contents of a file ...
s to extract meaningful text from the binary blob (for example, when a
Microsoft Word Microsoft Word is a word processing software developed by Microsoft. It was first released on October 25, 1983, under the name ''Multi-Tool Word'' for Xenix systems. Subsequent versions were later written for several other platforms includin ...
document is stored as an unstructured binary file in a database). The iFilters are hosted by the Filter Daemon process. Once the text is extracted, the Filter Daemon process breaks it up into a sequence of words and hands it over to the indexer. The indexer filters out ''noise words'', i.e., words like ''A'', ''And'', etc., which occur frequently and are not useful for search. With the remaining words, an
inverted index In computer science, an inverted index (also referred to as a postings list, postings file, or inverted file) is a database index storing a mapping from content, such as words or numbers, to its locations in a table, or in a document or a set of d ...
is created, associating each word with the columns they were found in. SQL Server itself includes a ''Gatherer'' component that monitors changes to tables and invokes the indexer in case of updates. When a full text query is received by the SQL Server query processor, it is handed over to the FTS query processor in the Search process. The FTS query processor breaks up the query into the constituent words, filters out the noise words, and uses an inbuilt
thesaurus A thesaurus (plural ''thesauri'' or ''thesauruses'') or synonym dictionary is a reference work for finding synonyms and sometimes antonyms of words. They are often used by writers to help find the best word to express an idea: Synonym diction ...
to find out the linguistic variants for each word. The words are then queried against the inverted index and a rank of their accurateness is computed. The results are returned to the client via the SQL Server process.


SQLCMD

SQLCMD is a command line application that comes with Microsoft SQL Server, and exposes the management features of SQL Server. It allows SQL queries to be written and executed from the command prompt. It can also act as a
scripting language A scripting language or script language is a programming language that is used to manipulate, customize, and automate the facilities of an existing system. Scripting languages are usually interpreted at runtime rather than compiled. A scripting ...
to create and run a set of SQL statements as a script. Such scripts are stored as a .sql file, and are used either for management of databases or to create the database schema during the deployment of a database. SQLCMD was introduced with SQL Server 2005 and has continued through SQL Server versions 2008, 2008 R2, 2012, 2014, 2016 and 2019. Its predecessor for earlier versions was OSQL and ISQL, which were functionally equivalent as it pertains to T-SQL execution, and many of the command line parameters are identical, although SQLCMD adds extra versatility.


Visual Studio

Microsoft Visual Studio Visual Studio is an integrated development environment (IDE) from Microsoft. It is used to develop computer programs including websites, web apps, web services and mobile apps. Visual Studio uses Microsoft software development platforms such a ...
includes native support for data programming with Microsoft SQL Server. It can be used to write and debug code to be executed by SQL CLR. It also includes a ''data designer'' that can be used to graphically create, view or edit database schemas. Queries can be created either visually or using code. SSMS 2008 onwards, provides
intellisense Intelligent code completion is a context-aware code completion feature in some programming environments that speeds up the process of coding applications by reducing typos and other common mistakes. Attempts at this are usually done through auto-c ...
for SQL queries as well.


SQL Server Management Studio

SQL Server Management Studio Microsoft SQL Server Management Studio (SSMS) is a software application developed by Microsoft that is used for configuring, managing, and administering all components within Microsoft SQL Server. First launched with Microsoft SQL Server 2005, ...
is a
GUI The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
tool included with SQL Server 2005 and later for configuring, managing, and administering all components within Microsoft SQL Server. The tool includes both script editors and graphical tools that work with objects and features of the server. SQL Server Management Studio replaces
Enterprise Manager Enterprise (or the archaic spelling Enterprize) may refer to: Business and economics Brands and enterprises * Enterprise GP Holdings, an energy holding company * Enterprise plc, a UK civil engineering and maintenance company * Enterprise ...
as the primary management interface for Microsoft SQL Server since SQL Server 2005. A version of SQL Server Management Studio is also available for SQL Server Express Edition, for which it is known as ''SQL Server Management Studio Express'' (SSMSE). A central feature of SQL Server Management Studio is the Object Explorer, which allows the user to browse, select, and act upon any of the objects within the server. It can be used to visually observe and analyze query plans and optimize the database performance, among others. SQL Server Management Studio can also be used to create a new database, alter any existing database schema by adding or modifying tables and indexes, or analyze performance. It includes the query windows which provide a GUI based interface to write and execute queries.


Azure Data Studio

Azure Data Studio is a cross platform query editor available as an optional download. The tool allows users to write queries; export query results; commit SQL scripts to
Git Git () is a distributed version control system: tracking changes in any set of files, usually used for coordinating work among programmers collaboratively developing source code during software development. Its goals include speed, data in ...
repositories and perform basic server diagnostics. Azure Data Studio supports Windows, Mac and Linux systems. It was released to General Availability in September 2018. Prior to release the preview version of the application was known as SQL Server Operations Studio.


Business Intelligence Development Studio

Business Intelligence Development Studio (BIDS) is the IDE from
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...
used for developing data analysis and
Business Intelligence Business intelligence (BI) comprises the strategies and technologies used by enterprises for the data analysis and management of business information. Common functions of business intelligence technologies include reporting, online analytical pr ...
solutions utilizing the Microsoft SQL Server Analysis Services, Reporting Services and Integration Services. It is based on the
Microsoft Visual Studio Visual Studio is an integrated development environment (IDE) from Microsoft. It is used to develop computer programs including websites, web apps, web services and mobile apps. Visual Studio uses Microsoft software development platforms such a ...
development environment but is customized with the SQL Server services-specific extensions and project types, including tools, controls and projects for reports (using Reporting Services),
Cubes In geometry, a cube is a three-dimensional space, three-dimensional solid object bounded by six square (geometry), square faces, Facet (geometry), facets or sides, with three meeting at each vertex (geometry), vertex. Viewed from a corner it i ...
and data mining structures (using Analysis Services). For SQL Server 2012 and later, this IDE has been renamed SQL Server Data Tools (SSDT).


See also

*
Comparison of relational database management systems The following tables compare general and technical information for a number of relational database management systems. Please see the individual products' articles for further information. Unless otherwise specified in footnotes, comparisons are b ...
* Comparison of object-relational database management systems *
Comparison of data modeling tools This article is a comparison of data modeling tools which are notable, including standalone, conventional data modeling tools and modeling tools supporting data modeling as part of a larger modeling environment. General Features {, c ...
*
List of relational database management systems This is a list of relational database management systems. List of software * 4th Dimension *Access Database Engine (formerly known as Jet Database Engine) *Adabas D *Airtable *Apache Derby *Apache Ignite * Aster Data *Amazon Aurora *Altibase * CA ...
* XLeratorDB


References


Further reading

* Lance Delano, Rajesh George et al. (2005). ''Wrox's SQL Server 2005 Express Edition Starter Kit (Programmer to Programmer)''. ''Microsoft Press''. . * Delaney, Kalen, et al. (2007). ''Inside SQL Server 2005: Query Tuning and Optimization''. ''Microsoft Press''. . * Ben-Gan, Itzik, et al. (2006). ''Inside Microsoft SQL Server 2005: T-SQL Programming''. ''Microsoft Press''. . * Klaus Elk (2018). ''SQL Server with C#''. .


External links

* * {{Microsoft, close Client-server database management systems Database management systems Microsoft database software Relational database management systems SQL Server Relational database management software for Linux