What is Data definition language?

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Data definition Language :-  it is a standard for commands that define the different structures in a database.

§  It creates , modify , and remove database objects such as tables , indexes , and users.

§  CREATE , ALTER , DROP  are some common data definition language.

§  It is used in database applications that are considered a subset of SQL( Structured Query Language)

§  However , a DDL(Data Definition Language) may also define other types of data , such as XML.

§  It has pre-defined syntax for describing data. For example  to build a new table by using  SQL syntax then  the  CREATE command is used , followed by parameters for the table name and column definitions.

§  It can also define the name of each column and the associated data type. Once a table is created the it can be modified by using ALTER command and to delete the table we can be use DROP  command.

§  Since , DDL is a subset of SQL , it does not include all the possible SQL command. For example , commands such as SELECT and INSERT are considered part of the data Manipulation Language(DML) , while access commands such as CONNECT and EXECUTE are part of the Data Control Language(DCL).

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