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In relational databases a virtual column is a table column whose value(s) is automatically computed using other columns values, or another deterministic expression. Virtual columns are defined of SQL:2003 as Generated Column, [1] and are only implemented by some DBMSs, like MariaDB, SQL Server, Oracle, PostgreSQL, SQLite and Firebird (database server) (COMPUTED BY syntax).
Connected Data Objects (CDO) is a free implementation of a Distributed Shared Model on top of the Eclipse Modeling Framework (EMF).. With CDO, programmers can easily enhance existing EMF models in such a way that they can be stored and subsequently maintained in a central model repository.
SQL Anywhere (formerly known as Sybase Adaptive Server Anywhere and Watcom SQL) Proprietary SQL Azure (Cloud SQL Server) Proprietary SQLBase: Proprietary SQLite: Public Domain SQream DB: Proprietary SAP Advantage Database Server (formerly known as Sybase Advantage Database Server) Proprietary Teradata: Proprietary TiDB: Apache License 2.0 ...
In all these cases, however, the database designer does not have to perform 6NF normalization manually by creating separate tables. Some DBMSs that are specialized for warehousing, such as Sybase IQ , use columnar storage by default, but the designer still sees only a single multi-column table.
In SQL, an INNER JOIN prevents a cartesian product from occurring when there are two tables in a query. For each table added to a SQL Query, one additional INNER JOIN is added to prevent a cartesian product. Thus, for N tables in an SQL query, there must be N−1 INNER JOINS to prevent a cartesian product.
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.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time said table is accessed.