What is difference between DELETE and TRUNCATE commands?

Posted by

To view Verified answers click on the button below.

Delete command removes the rows from a table based on the condition that we provide
with a WHERE clause. Truncate will actually remove all the rows from a table and there
will be no data in the table after we run the truncate command.

1. 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, its
columns, constraints, indexes and so on, remains. The counter used by an
identity for new rows is reset to the seed for the column.

4. You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY
constraint. Because TRUNCATE TABLE is not logged, it cannot activate a
trigger.

5. TRUNCATE cannot be rolled back.

6. TRUNCATE is DDL Command.

7. TRUNCATE Resets identity of the table

2. DELETE:

1. DELETE removes rows one at a time and records an entry in the transaction
log for each deleted row.

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.

6. DELETE is DML Command.

7. DELETE does not reset identity of the table.

Note: DELETE and TRUNCATE both can be rolled back when surrounded by TRANSACTION
if the current session is not closed. If TRUNCATE is written in Query Editor surrounded by
TRANSACTION and if session is closed, it can not be rolled back but DELETE can be rolled
back.