TRUNCATE TABLE NOT WORKING AFTER DROPPING CONSTRAINTS

Question

Hi,
I have a table with a foreign key constraint. I know you can't truncate tables when there are foreign key constraints. So I drop the constraints before running the TRUNCATE TABLE command. But SQL Server is still stating there are foreign key constraints
even after they have just been dropped.
When I use SQL Server Management Studio to generate a drop & create script on this table or any other table with an FK consttaint, the generated script fails stating that there are still foreign key constraints??
I have the same problem for every table that has FK constraints, for those without FK, TRUNCATE table works without issues.
The end goal is to reset the identity value of the primary key. Since DBCC does not work on Azure, TRUNCATE TABLE is the only way left, especially if you can't even drop and recreate tables with FK constraints.
What am I missing here?
Peter

Answer 1

Hi,
Thanks for posting here.
TRUNCATE TABLE is similar to the DELETE statement with no WHERE clause; however, TRUNCATE TABLE is faster and uses fewer system and transaction log resources.
TRUNCATE TABLE removes all rows from a table, but the table structure and its columns, constraints, indexes, and so on remain. To remove the table definition in addition to its data, use the DROP TABLE statement.
If the table contains an identity column, the counter for that column is reset to the seed value defined for the column. If no seed was defined, the default value 1 is used. To retain the identity counter, use DELETE instead.
Restrictions
You cannot use TRUNCATE TABLE on tables that:
•Are referenced by a FOREIGN KEY constraint. (You can truncate a table that has a foreign key that references itself.)
•Participate in an indexed view.
•Are published by using transactional replication or merge replication.
For tables with one or more of these characteristics, use the DELETE statement instead.
TRUNCATE TABLE cannot activate a trigger because the operation does not log individual row deletions. For more information, see CREATE TRIGGER (Transact-SQL).
Truncating Large Tables
Microsoft SQL Server has the ability to drop or truncate tables that have more than 128 extents without holding simultaneous locks on all the extents required for the drop.
Permissions--------------------------------------------------------------------------------
 The minimum permission required is ALTER on table_name. TRUNCATE TABLE permissions default to the table owner, members of the sysadmin fixed server role, and the db_owner and db_ddladmin fixed database roles, and are not transferable. However, you
can incorporate the TRUNCATE TABLE statement within a module, such as a stored procedure, and grant appropriate permissions to the module using the EXECUTE AS clause.
You cannot truncate a table which has an FK constraint on it.
Typically my process for this is:
Drop the constraints
Trunc the table
Recreate the constraints.
Hope this helps you.
Girish Prajwal