How do I drop a foreign key constraint only if it exists in sql server?

Question

I can drop a table if it exists using the following code but do not know how to do the same with a constraint:

IF EXISTS(SELECT 1 FROM sys.objects WHERE OBJE         


        

Answer 1

In SQL Server 2016 you can use DROP IF EXISTS:

CREATE TABLE t(id int primary key, 
               parentid int
                    constraint tpartnt foreign key references t(id))
GO
ALTER TABLE t
DROP CONSTRAINT IF EXISTS tpartnt
GO
DROP TABLE IF EXISTS t

See http://blogs.msdn.com/b/sqlserverstorageengine/archive/2015/11/03/drop-if-exists-new-thing-in-sql-server-2016.aspx