Information processing systems--Database language SQL with integrity enhancement

2Scope / Description

This standard specifies the syntax and semantics of two database languages: 1) Schema definition language (SQL-DDL), which is used to declare the structure and integrity constraints of SQL databases. 2) Module language and data manipulation language (SQL-DML), which are used to declare database procedures and executable statements of specific database applications. This standard defines the logical data structure and basic operations of SQL databases, and it provides capabilities in database design, access, maintenance, control and protection. This International Standard provides a means for the migration of database definitions and applications between mutually conforming implementations. This standard specifies two levels and a single integrity-enhancing characteristic. Level 2 is the full SQL database language except for the integrity-enhancing features, and Level 1 is a subset of Level 2 as defined in Chapter 9, "Levels." Note: The newly added part of the SQL language is planned to be used as a supplement to this standard. The main topics to be considered in the Supplement include enhanced transaction management, specification of certain implementer-defined rules, enhanced character handling facilities, and support of national character sets. This integrity enhancement feature includes the following three ways specified: 1) Reference constraints that must be satisfied between tables; 2) Validation constraints applied to rows in tables; 3) Default values for columns when inserting a row into a table. The appendices of this standard indicate the embedded syntax of the SQL data manipulation language included in other standard applications. The embedded syntax described above is defined as a simplified representation of a standard application program in which embedded SQL statements are replaced by explicit "calls" of the database procedures containing the SQL statements. This standard applies to implementations in an environment that can include application programming languages, end-user query languages, report generators, data dictionary systems, library systems, distributed communication systems, and various Tools for design, data management, and performance optimization.