Difference B/W Truncate,Delete and Drop Table

Posted Date: 19 Jun 2008	Resource Type: Articles	Category: Databases
Author: Gaurav Agrawal	Member Level: Silver
Rating:	Points: 5

DROP : Drops the table records and structure from the DB schema. Nothing else is leftout. Can't rollback.

Truncate

: Clears the records from the table but the table structure still remains.
Can't roll back. Clears all records from the table because we can not use where clause in truncate command.It is fast because it delete all rows at a time not onr by one.and will make only one entry in log file for deleting all the row, THAT ALSO WE CAN ROLL BACK. it will reset Identity value of the identity column

Delete from

: deletes the rows based on the query or will delete all the rows if no "where" clause is given. Can roll back i.e deleted records can restored. it will not reset identity value of identity column
This operation is slow as compared to drop and truncate command because it makes a entry for every deleted row into the transaction log file and all deleted records can be rolled back after deletion.
in delete it will make one entry for each row to be deleted. while truncate will make only one entry for all the rows. in delete it will free all the datapages by deleting the contents of the data pages. while in truncate it will delete the pointer to those datapages for all deleted rows

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Author: sangeetha 12 May 2009		Member Level: Gold Points : 2
DELETE TABLE is a logged operation, so the deletion of each row gets logged in the transaction log, which makes it slow. TRUNCATE TABLE also deletes all the rows in a table, but it won't log the deletion of each row, instead it logs the deallocation of the data pages of the table, which makes it faster. Of course, TRUNCATE TABLE can be rolled back. DROP : Drops the table records and structure from the DB schema. Nothing else is leftout. Can't rollback.

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Difference B/W Truncate,Delete and Drop Table

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