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Attribute (database)
In a relational database, a column is a set of data values of a particular type, one value for each row of a table.The term "column" also has equivalent applications in other, more generic contexts. See e.g., Flat file database, Table (information). A column may contain text values, numbers, or even pointers to files in the operating system. Columns typically contain simple types, though some relational database systems allow columns to contain more complex data types, such as whole documents, images, or even video clips. A column can also be called an attribute. Each row would provide a data value for each column and would then be understood as a single structured data value. For example, a database that represents company contact information might have the following columns: ID, Company Name, Address Line 1, Address Line 2, City, and Postal Code. More formally, a row is a tuple containing a specific value for each column, for example: (1234, 'Big Company Inc.', '123 East Examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relational Database
A relational database (RDB) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. A Relational Database Management System (RDBMS) is a type of database management system that stores data in a structured format using rows and columns. Many relational database systems are equipped with the option of using SQL (Structured Query Language) for querying and updating the database. History The concept of relational database was defined by E. F. Codd at IBM in 1970. Codd introduced the term ''relational'' in his research paper "A Relational Model of Data for Large Shared Data Banks". In this paper and later papers, he defined what he meant by ''relation''. One well-known definition of what constitutes a relational database system is composed of Codd's 12 rules. However, no commercial implementations of the relational model conform to all of Codd's rules, so the term has gradually come to describe a broader class of database systems, which at a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key–value Database
A key–value database, or key–value store, is a data storage paradigm designed for storing, retrieving, and managing associative arrays, a data structure more commonly known today as a ''dictionary'' or ''hash table''. Dictionaries contain a collection of '' objects'', or '' records'', which in turn have many different ''fields'' within them, each containing data. These records are stored and retrieved using a ''key'' that uniquely identifies the record, and is used to find the data within the database. Key–value databases work in a very different fashion from the better known relational databases (RDB). RDBs predefine the data structure in the database as a series of tables containing fields with well defined data types. Exposing the data types to the database program allows it to apply a number of optimizations. In contrast, key–value systems treat the data as a single opaque collection, which may have different fields for every record. This offers considerable flexibi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
行 (數據庫)
Radical 144 or radical walk enclosure () meaning "" or "" is one of the 29 Kangxi radicals (214 radicals in total) composed of 6 strokes. In the ''Kangxi Dictionary'', there are 53 characters (out of 49,030) to be found under this radical. is not used as an indexing component (radical) in Simplified Chinese. Characters with this radical are classified under radical 彳 (No. 60 in the ''Kangxi Dictionary''; No. 41 in the ''Table of Indexing Chinese Character Components'') in Simplified Chinese. Evolution File:行-oracle.svg, Oracle bone script character File:行-bronze.svg, Bronze script character File:行-bigseal.svg, Large seal script character File:行-seal.svg, Small seal script character Derived characters Sinogram The radical is also used as an independent Chinese character. It is one of the kyōiku kanji or kanji taught in elementary school in Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Column Groups And Row Groups
In tables and matrices, a column group or row group usually refers to a subset of columns or rows, respectively. Short names or notational names include col group or colgroup, and row group or rowgroup. They can have varying uses depending on context: * In mathematics, a partitioned matrix is an interpretation of a matrix as being broken down into submatrices which may be more precisely referred to as a collection of row groups and column groups * In web development, colgroup is a standard HTML attribute and an HTML event attribute, for example used for color formatting of entire columns in HTML tables. The colgroup tag acts as a "parent container of one or more elements". Rowgroup is another HTML attribute. * In reporting (including business reporting, data reporting and financial reporting), colgroups and rowgroups can be used for constructing tables and matrices which dynamically adjusts the size of their columns and rows, respectively, by displaying the set of columns in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Query Language
A query language, also known as data query language or database query language (DQL), is a computer language used to make queries in databases and information systems. In database systems, query languages rely on strict theory to retrieve information. A well known example is the Structured Query Language (SQL). Types Broadly, query languages can be classified according to whether they are ''database'' query languages or ''information retrieval'' query languages. The difference is that a database query language attempts to give factual answers to factual questions, while an information retrieval query language attempts to find documents containing information that is relevant to an area of inquiry. Other types of query languages include: * Full-text. The simplest query language is treating all terms as bag of words that are to be matched with the postings in the inverted index and where subsequently ranking models are applied to retrieve the most relevant documents. Only tokens ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Data Store
A distributed data store is a computer network where information is stored on more than one node, often in a replicated fashion. It is usually specifically used to refer to either a distributed database where users store information on a ''number of nodes'', or a computer network in which users store information on a ''number of peer network nodes''. Distributed databases Distributed databases are usually non-relational databases that enable a quick access to data over a large number of nodes. Some distributed databases expose rich query abilities while others are limited to a key-value store semantics. Examples of limited distributed databases are Google's Bigtable, which is much more than a distributed file system or a peer-to-peer network, Amazon's Dynamo and Microsoft Azure Storage. As the ability of arbitrary querying is not as important as the availability, designers of distributed data stores have increased the latter at an expense of consistency. But the high-speed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Column (data Store)
A column of a distributed data store is a NoSQL object of the lowest level in a keyspace. It is a tuple (a key–value pair) consisting of three elements: * Unique name: Used to reference the column * Value: The content of the column. It can have different types, like AsciiType, LongType, TimeUUIDType, UTF8Type among others. * Timestamp: The system timestamp used to determine the valid content. Usage A column is used as a store for the value and has a timestamp that is used to differentiate the valid content from stale ones. According to the CAP theorem, distributed data stores cannot guarantee consistency, as availability and partition tolerance are more important issues. Therefore, the data store or the application programmer will use the timestamp to find out which of the stored values in the backup nodes are up-to-date. Some data stores, like Riak, may use the more sophisticated vector clock instead of the timestamp to resolve stale information. Differences from a relat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Column-oriented DBMS
Data orientation is the representation of tabular data in a linear memory model such as in-disk or in-memory. The two most common representations are column-oriented (columnar format) and row-oriented (row format). The choice of data orientation is a trade-off and an architectural decision in databases, query engines, and numerical simulations. As a result of these tradeoffs, row-oriented formats are more commonly used in Online transaction processing (OLTP) and column-oriented formats are more commonly used in Online analytical processing (OLAP). Examples of column-oriented formats include Apache ORC, Apache Parquet, Apache Arrow, formats used by BigQuery, Amazon Redshift and Snowflake. Predominant examples of row-oriented formats include CSV, formats used in most relational databases, the in-memory format of Apache Spark, and Apache Avro. Description Tabular data is two dimensional — data is modeled as rows and columns. However, computer systems represent d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dbms
In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS additionally encompasses the core facilities provided to administer the database. The sum total of the database, the DBMS and the associated applications can be referred to as a database system. Often the term "database" is also used loosely to refer to any of the DBMS, the database system or an application associated with the database. Before digital storage and retrieval of data have become widespread, index cards were used for data storage in a wide range of applications and environments: in the home to record and store recipes, shopping lists, contact information and other organizational data; in business to record presentation notes, project research and notes, and contact information; in schools as flash card ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data
Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted formally. A datum is an individual value in a collection of data. Data are usually organized into structures such as tables that provide additional context and meaning, and may themselves be used as data in larger structures. Data may be used as variables in a computational process. Data may represent abstract ideas or concrete measurements. Data are commonly used in scientific research, economics, and virtually every other form of human organizational activity. Examples of data sets include price indices (such as the consumer price index), unemployment rates, literacy rates, and census data. In this context, data represent the raw facts and figures from which useful information can be extracted. Data are collected using technique ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primitive Data 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 programs must use. Most processors support a similar set of primitive data types, although the specific representations vary. More generally, ''primitive data types'' may refer to the standard data types built into a programming language (built-in types). Data types which are not primitive are referred to as ''derived'' or ''composite''. Primitive types are almost always value types, but composite types may also be value types. Common primitive data types The most common primitive types are those used and supported by computer hardware, such as integers of various sizes, floating-point numbers, and Boolean logical values. Operations on such types are usually quite efficient. Primitive data types which are native to the processor have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Table (information)
A table is an arrangement of information or data, typically in rows and columns, or possibly in a more complex structure. Tables are widely used in communication, research, and data analysis. Tables appear in print media, handwritten notes, computer software, architectural ornamentation, traffic signs, and many other places. The precise conventions and terminology for describing tables vary depending on the context. Further, tables differ significantly in variety, structure, flexibility, notation, representation and use. Information or data conveyed in table form is said to be in tabular format (adjective). In books and technical articles, tables are typically presented apart from the main text in numbered and captioned floating blocks. Basic description A table consists of an ordered arrangement of rows and columns. This is a simplified description of the most basic kind of table. Certain considerations follow from this simplified description: * the term row has several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
