DDL
Data Definition Language statements are
used to define the database structure or schema. Examples:
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CREATE - to create objects in the database
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ALTER - alters the structure of the database
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DROP - delete objects from the database
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TRUNCATE - remove all records from a table,
including all spaces allocated for the records are removed
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COMMENT - add comments to the data dictionary
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RENAME - rename an object
DML
Data Manipulation Language statements are used for managing data within schema
objects. Examples:
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SELECT - retrieve data from the a database
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INSERT - insert data into a table
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UPDATE - updates existing data within a table
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DELETE - deletes all records from a table, the
space for the records remain
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CALL - call a PL/SQL or Java subprogram
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EXPLAIN PLAN - explain access path to data
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LOCK TABLE - control concurrency
DCL
Data Control Language statements are generally used to provide control/access/privileges to
user over database. Examples:
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GRANT - gives user's access privileges to
database
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REVOKE - withdraw access privileges given with
the GRANT command
TCL
Transaction
Control statements are used to manage the
changes made by DML statements. It allows statements to be grouped together
into logical transactions. Examples:
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COMMIT - save work done
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SAVEPOINT - identify a point in a transaction
to which you can later roll back
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ROLLBACK - restore database to original state
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SET TRANSACTION - Change transaction options
like isolation level and what rollback segment to use
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