|
Enhanced Entity–relationship Model
The enhanced entity–relationship (EER) model (or extended entity–relationship model) in computer science is a high-level or conceptual data model incorporating extensions to the original entity–relationship (ER) model, used in the design of databases. It was developed to reflect more precisely the properties and constraints that are found in more complex databases, such as in engineering design and manufacturing ( CAD/CAM), telecommunications, complex software systems and geographic information systems (GIS). Mechanics The EER model includes all of the concepts introduced by the ER model. Additionally it includes the concepts of a subclass and superclass ( Is-a), along with the concepts of specialization and generalization. Furthermore, it introduces the concept of a union type or category, which represents a collection of objects that is the union of objects of different entity types. The EER model also includes EER diagrams that are conceptual models that accuratel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conceptual Schema
A conceptual schema or conceptual data model is a high-level description of informational needs underlying the design of a database. It typically includes only the core concepts and the main relationships among them. This is a high-level model with insufficient detail to build a complete, functional database. It describes the structure of the whole database for a group of users. The conceptual model is also known as the data model that can be used to describe the conceptual schema when a database system is implemented. It hides the internal details of physical storage and targets the description of entities, datatypes, relationships and constraints. Overview A conceptual schema is a map of concepts and their relationships used for databases. This describes the semantics of an organization and represents a series of assertions about its nature. Specifically, it describes the things of significance to an organization (''entity classes''), about which it is inclined to collec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Union (computer Science)
Union commonly refers to: * Trade union, an organization of workers * Union (set theory), in mathematics, a fundamental operation on sets Union may also refer to: Arts and entertainment Music * Union (band), an American rock group ** ''Union'' (Union album), 1998 * ''Union'' (Chara album), 2007 * ''Union'' (Toni Childs album), 1988 * ''Union'' (Cuff the Duke album), 2012 * ''Union'' (Paradoxical Frog album), 2011 * ''Union'', a 2001 album by Puya * ''Union'', a 2001 album by Rasa * ''Union'' (Son Volt album), 2019 * ''Union'' (The Boxer Rebellion album), 2009 * ''Union'' (Yes album), 1991 * "Union" (Black Eyed Peas song), 2005 Other uses in arts and entertainment * ''Union'' (film), a labor documentary released in 2024 * ''Union'' (Star Wars), a Dark Horse comics limited series * Union, in the fictional Alliance–Union universe of C. J. Cherryh * ''Union (Horse with Two Discs)'', a bronze sculpture by Christopher Le Brun, 1999–2000 * The Union (Marvel Team), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structured Type
The SQL:1999 standard introduced a number of object–relational database features into SQL, chiefly among them structured user-defined types, usually called just structured types. These can be defined either in plain SQL with CREATE TYPE but also in Java via SQL/JRT. SQL structured types allow single inheritance. Structured types are supported to varying degrees in Oracle Database, IBM Db2, PostgreSQL and Microsoft SQL Server, although the latter only allows structured types defined in CLR. SQL examples Object structured type In order to define a custom structure type using Oracle Database one could use statements such as these: CREATE TYPE Person_Type AS OBJECT ( person_title VARCHAR2(10), person_first_name VARCHAR2(20), person_last_name VARCHAR2(20), ) NOT FINAL; Such structure type can be then used to create a table that would also hold all columns defined in ''Person_Type'': CREATE TABLE Person_Table OF Person_Type; Custom structure types support inherita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slowly Changing Dimension
In data management and data warehousing, a slowly changing dimension (SCD) is a dimension that stores data which, while generally stable, may change over time, often in an unpredictable manner. This contrasts with a rapidly changing dimension, such as transactional parameters like customer ID, product ID, quantity, and price, which undergo frequent updates. Common examples of SCDs include geographical locations, customer details, or product attributes. Various methodologies address the complexities of SCD management. The Kimball Toolkit has popularized a categorization of techniques for handling SCD attributes as Types 1 through 6. These range from simple overwrites (Type 1), to creating new rows for each change (Type 2), adding new attributes (Type 3), maintaining separate history tables (Type 4), or employing hybrid approaches (Type 6 and 7). Type 0 is available to model an attribute as not really changing at all. Each type offers a trade-off between historical accuracy, data ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object–relational Database
An object–relational database (ORD), or object–relational database management system (ORDBMS), is a database management system (DBMS) similar to a relational database, but with an object-oriented database model: objects, classes and inheritance are directly supported in database schemas and in the query language. Also, as with pure relational systems, it supports extension of the data model with custom data types and methods. An object–relational database can be said to provide a middle ground between relational databases and object-oriented databases. In object–relational databases, the approach is essentially that of relational databases: the data resides in the database and is manipulated collectively with queries in a query language; at the other extreme are OODBMSes in which the database is essentially a persistent object store for software written in an object-oriented programming language, with an application programming interface API for storing and retrievi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PowerDesigner
SAP PowerDesigner (or PowerDesigner) is a collaborative enterprise modelling tool produced by Sybase, currently owned by SAP. It can run either under Microsoft Windows as a native application or in an Eclipse environment through a plugin. It supports model-driven architecture software design, and stores models using a variety of file extensions, such as .bpm, .cdm and .pdm. The internal file structure can be either XML or a compressed binary file format. It can also store models in a database repository. The PowerDesigner data modeling tool's market share in 2002 was 39%. It is priced from US$3,000 to $7,500 per developer seat. Features PowerDesigner includes support for: *Business Process Modeling (''ProcessAnalyst'') supporting BPMN * Code generation (Java, C#, VB .NET, Hibernate, EJB3, NHibernate, JSF, WinForm (.NET and .NET CF), PowerBuilder, ...) *Data modeling (works with most major RDBMS systems) *Data Warehouse Modeling (''WarehouseArchitect'') *Eclipse plugin * Ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object–relational Mapping
Object–relational mapping (ORM, O/RM, and O/R mapping tool) in computer science is a programming technique for converting data between a relational database and the memory (usually the heap) of an object-oriented programming language. This creates, in effect, a virtual object database that can be used from within the programming language. In object-oriented programming, data-management tasks act on objects that combine scalar values into objects. For example, consider an address book entry that represents a single person along with zero or more phone numbers and zero or more addresses. This could be modeled in an object-oriented implementation by a "Person object" with an attribute/field to hold each data item that the entry comprises: the person's name, a list of phone numbers, and a list of addresses. The list of phone numbers would itself contain "PhoneNumber objects" and so on. Each such address-book entry is treated as a single object by the programming language ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skipper (computer Software)
Skipper is a visualization tool and Automatic programming, code/schema generator for PHP O/R mapper, ORM frameworks like Doctrine (PHP), Doctrine2, Doctrine (PHP), Doctrine, Propel, and CakePHP, which are used to create database abstraction layer. Skipper is developed by Czech company Inventic, s.r.o. based in Brno, and was known as ORM Designer prior to rebranding in 2014. Overview * Generates visual model from the schema definition files * Repetitive import/export of schema definitions in supported formats (XML, YML, PHP annotations) * Schema definition files are automatically generated from the visual model * Visual representation uses ER diagram extended by concepts of Inheritance (object-oriented programming), inheritance and Many-to-many (data model), many-to-many * Supports customization using .xml configuration files and JavaScript * Does not support direct connections to the database * Crude and simplistic visual representation and menus Architecture Skipper was built ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MySQL Workbench
MySQL Workbench is a visual database design tool that integrates SQL development, administration, database design, creation and maintenance into a single integrated development environment for the MySQL database system. It is the successor to DBDesigner 4 from fabFORCE.net, and replaces the previous package of software, MySQL GUI Tools Bundle. History fabFORCE.net DBDesigner4 DBDesigner4 is an open source visual database design and querying tool for the MySQL database released under the GPL. It was written in 2002/2003 by the Austrian programmer Michael G. Zinner for his fabFORCE.net platform using Delphi 7 / Kylix 3. While being a physical-modeling only tool DBDesigner4 offers a comprehensive feature set including reverse engineering of MySQL databases, model-to-database synchronization, model poster printing, basic version control of schema models and a SQL query builder. It is available for MS Windows, Mac OS X and Linux. In late 2003, Zinner was approached by representa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entity–relationship Model
An entity–relationship model (or ER model) describes interrelated things of interest in a specific domain of knowledge. A basic ER model is composed of entity types (which classify the things of interest) and specifies relationships that can exist between entities (instances of those entity types). In software engineering, an ER model is commonly formed to represent things a business needs to remember in order to perform business processes. Consequently, the ER model becomes an abstract data model, that defines a data or information structure that can be implemented in a database, typically a relational database. Entity–relationship modeling was developed for database and design by Peter Chen and published in a 1976 paper, with variants of the idea existing previously. Today it is commonly used for teaching students the basics of database structure. Some ER models show super and subtype entities connected by generalization-specialization relationships, and an ER model can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attribute (computing)
In computing, an attribute is a specification that defines a property of an object, element, or file. It may also refer to or set the specific value for a given instance of such. For clarity, attributes should more correctly be considered metadata. An attribute is frequently and generally a property of a property. However, in actual usage, the term attribute can and is often treated as equivalent to a property depending on the technology being discussed. An attribute of an object usually consists of a name and a value. For an element these can be a type and class name, while for a file these can be a name and an extension, respectively. Rules and typing * Rules: Each named attribute has an associated set of rules called operations: For example, one doesn't sum characters or manipulate and process an integer array the same way as an image object. Neither does one process text as if it was type of floating point ( decimal numbers). * Data types: It follows that an object d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entity
An entity is something that Existence, exists as itself. It does not need to be of material existence. In particular, abstractions and legal fictions are usually regarded as entities. In general, there is also no presumption that an entity is Life, animate, or present. The verb tense of this form is to 'entitize' - meaning to convert into an entity; to perceive as tangible or alive. The term is broad in scope and may refer to animals; natural features such as mountains; inanimate objects such as tables; numbers or sets as symbols written on a paper; human contrivances such as laws, corporations and academic disciplines; or supernatural beings such as gods and spirits. The adjectival form is ''entitative''. Etymology The word ''entity'' is derived from the Latin ''entitas'', which in turn derives from the Latin ''ens'' meaning "being" or "existing" (compare English ''essence''). ''Entity'' may hence literally be taken to mean "thing which exists". In philosophy Ontology is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
