8. SQL
The Structured Query Language (SQL) is a language for
working with information that has been stored in a database.
SQL has three parts:
the Data Manipulation
Language (DML)
concerns adding information to a database, modifying the
information, and extracting information from a database;
the Data Definition Language (DDL)
is concerned with the structure
of a database (creating tables); and the Data Control
Language (DCL)
is concerned with administration of a database
(deciding who gets what sort of access to which parts of the
database).
This chapter is mostly focused on the SELECT command, which
is the part of the DML that is used to extract information from a database,
but other useful SQL commands are also mentioned briefly in Section
8.3.
Subsections
Paul Murrell
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