DELETE and TRUNCATE Command In SQL


Delete command removes the rows from a table based on the condition that we provide with a WHERE clause, whereas Truncate command will actually remove all the rows from a table.

DELETE:

1. DELETE removes rows one at a time and records an entry in the transaction log for each deleted row. So it’s comparatively slower than TRUNCATE.

2. If you want to retain the identity counter, use DELETE instead. If you want to remove table definition and its data, use the DROP TABLE statement.

3. DELETE Can be used with or without a WHERE clause

4. DELETE Activates Triggers.

5. DELETE Can be Rolled back using logs.

6. DELETE is Data Manipulation Language (DML) Command.

7. DELETE does not reset identity of the table.

The Syntax of a DELETE statement is:

DELETE FROM TableName [WHERE condition]

TRUNCATE:

1. TRUNCATE is faster and uses fewer system and transaction log resources than DELETE.

2. TRUNCATE removes the data by deallocating the data pages used to store the table’s data, and only the page deallocations are recorded in the transaction log.

3. TRUNCATE removes all rows from a table, but the table structure and its columns, constraints, indexes remain.

4. You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint.

5. Because TRUNCATE TABLE is not logged, it cannot activate a trigger.

6. TRUNCATE can not be Rolled back using logs.

7. TRUNCATE is Data Definition Language (DDL) Command.

8. TRUNCATE Resets identity of the table. The counter used by an identity for new rows is reset to the seed for the column.

The Syntax of a TRUNCATE statement is:

TRUNCATE TABLE TableName

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