Question

I am using Sql Server Management Studio 2008.

When I try to truncate a table using the following command

truncate table MyTable

it gives me an error saying

Cannot truncate table ‘dbo.MyTable’ because it is being referenced by a FOREIGN KEY constraint.

I know I have a foriegn Key in this table.

Now when I do the following

• Right click on table and select Edit Top 200 Rows
• Right on any records from the table
• and hit Delete, it gets deleted.

I am confused with this behaviour, please can some one let me know how and why this happens and how do I delete using truncate statement.

Thanks

Answer 1

Basicly because there is a difference between DELETE and TRUNCATE

If you could do that even a simple delete would work for those records. (If there is no reference on them, or if an ON DELETE statement is declared on the other table which made the reference to MyTable)

DELETE FROM dbo.MyTable

With the TRUNCATE you can’t do that. It is more then a DELETE. You have to remove the CONSTRAINT first and then you can make the Truncate. A Truncate is not allowed on a table which referenced by a forign_key.

And for example an other difference a Truncate command reserts the IDENTITY columns as well, but a DELETE not.

Here is a good article about it:

The difference in TRUNCATE and DELETE in Sql Server