Relation database are based upon the relational model and managed by a RDBMMS. SQL is the language which is used for both data dentition and data manipulation. It is both set oriented and declarative. Indeed, as opposed to record oriented database languages, SQL can retrieve many records at a time. Furthermore, you only need to specify which data to retrieve in contrast to procedural database languages which also require to explicitly specifying the access path to the data. In addition, it has facilities for defining views on the database, for specifying security and authorization, for defining integrity constraints, and for specifying transaction controls.

Various versions have been introduced. Each relational database vendor provides its own implementation of SQL. Whereby typically the bulk of the standard is implemented, complemented with some vendor specific things, SQL can be used interactively and embedded.

SQL is the language of choice in the relational database environment. It can be used for both data definition as well as data manipulation. As a data definition language or DDL, it has a create table statement to define a logical scheme. Create database, create table space and index statements for the physical scheme and the Create view statement for the external scheme. SQL allows retrieving the data using a Select … From … statement. It is possible to add easily data by using the insert … Into function. It is also possible to use the Update or Delete function.

  • Free form language: no specific notation is required as was the case for legacy programming language.
  • Most SQL implementations are case intensive.
  • Several commercial implementations exist, each providing their own character.