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MORE ON DATABASE 5
Data in a database can be stored and manipulated by using SQL. SQL is Structured Query Language
for storing, manipulating and retrieving data from a database. In this chapter, we will learn about
different type of commands.
TYPES OF DATABASE COMMANDS
S uses various commands to perform different operations on a database. Such commands are
categorised into:
ata efinition anguage ata Manipulation anguage M
ata ontrol anguage ransaction ontrol anguage
ata efinition anguage
ata efinition anguage or ata escription anguage is a standard for commands
that define the different structures in a database. statements create modify and remove
database objects such as tables, indexes and users. Common DDL statements are CREATE, ALTER,
TRUNCATE, RENAME and DROP.
ata Mani ulation anguage M
ata Manipulation language M is a language that enables users to retrieve update insert and
delete data in a database. Common DML statements are SELECT, UPDATE, INSERT INTO and DELETE.
ata ontrol anguage
A Data Control Language is a language that has various commands which are used to grant and
take back authority from any database user. Some DCL statements are Grant and Revoke.
Transaction ontrol anguage T
A Transaction Control Language is a language that has various commands which are used to
manage transactions in the database. These are used to manage the changes made by DML
statements. Some TCL statements are Commit, Savepoint and Rollback.
Do you know?
popular data manipulation language is Structured uery anguage S .
DATABASES AND OPERATORS
data type defines a sort of value that a column should contain. In a database table every column
must have a name and data type.
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