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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.
Normal-cardinality column values are typically names, street addresses, or vehicle types. An example of a data table column with normal-cardinality would be a CUSTOMER table with a column named LAST_NAME, containing the last names of customers. While some people have common last names, such as Smith, others have uncommon last names.
It is a collection of character data in a database management system, usually stored in a separate location that is referenced in the table itself. Oracle and IBM Db2 provide a construct explicitly named CLOB, [1] [2] and the majority of other database systems support some form of the concept, often labeled as text, memo or long character fields.
Though database systems use SQL, they also have their own additional proprietary extensions that are usually only used on their system. For example, Microsoft SQL server uses Transact-SQL (T-SQL), which is an extension of SQL. Similarly, Oracle uses PL-SQL, which an Oracle-specific SQL extension.
In the SQL 1992 specification, the types of components that can be created are schemas, tables, views, domains, character sets, collations, translations, and assertions. [2] Many implementations extend the syntax to allow creation of additional elements, such as indexes and user profiles.
In computer programming, a naming convention is a set of rules for choosing the character sequence to be used for identifiers which denote variables, types, functions, and other entities in source code and documentation. Reasons for using a naming convention (as opposed to allowing programmers to choose any character sequence) include the ...
A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...