TCL

Transaction Control Langauge : ( TCL )
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Used to control the changes made to the database.

Commit
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Used to save the changes made to the database.

2 Types

  a) Implicit Commit ( DDL ) : Applied by oracle automatically whenever DDL statements are performed .

  b) Explicit Commit ( DML ) : Provided by user after performing DML statements on database objects like  Table , View , Synonym .

commit will release the resources in logical memory and improve the performance of server.

set autocommit on -- Automatically activates the commit stmt after every DML stmt.

delete from emp; commit compleate

set autocommit off ( default )


Rollback
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used to cancel the uncommited transactions( DML ) on database objects.
Not applicable for DDL stmts.


Savepoint
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Used to identify the transactions performed previously.

Used to bookmark the transactions for further reference.

They are stored in Logical memory only. Commit / Rollback will clear the savepoints.