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Reserved words in SQL and related products In SQL:2023 [3] In IBM Db2 13 [4] In Mimer SQL 11.0 [5] In MySQL 8.0 [6] In Oracle Database 23c [7] In PostgreSQL 16 [1] In Microsoft SQL Server 2022 [2]
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
PL/pgSQL (Procedural Language/PostgreSQL) is a procedural programming language supported by the PostgreSQL ORDBMS. It closely resembles Oracle 's PL/SQL language. Implemented by Jan Wieck, PL/pgSQL first appeared with PostgreSQL 6.4, released on October 30, 1998. [ 1 ]
by adding a SQL window function to the SELECT-statement; ISO SQL:2008 introduced the FETCH FIRST clause. According to PostgreSQL v.9 documentation, an SQL window function "performs a calculation across a set of table rows that are somehow related to the current row", in a way similar to aggregate functions. [7]
PostgreSQL (/ ˌ p oʊ s t ɡ r ɛ s k j u ˈ ɛ l / POHST-gres-kew-EL) [11] [12] also known as Postgres, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance. PostgreSQL features transactions with atomicity, consistency, isolation, durability properties, automatically updatable ...
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).
In the context of SQL, data definition or data description language (DDL) is a syntax for creating and modifying database objects such as tables, indices, and users. DDL statements are similar to a computer programming language for defining data structures , especially database schemas .
A function is a subprogram written to perform certain computations. A scalar function returns only one value (or NULL), whereas a table function returns a (relational) table comprising zero or more rows, each row with one or more columns. Functions must return a value (using the RETURN keyword), but for stored procedures this is not mandatory.