How to check if a Constraint exists in Sql server?

Question

I have this sql:

ALTER TABLE dbo.ChannelPlayerSkins
    DROP CONSTRAINT FK_ChannelPlayerSkins_Channels

but apparently, on some other databa

Answer 1

Just something to watch out for......

In SQL Server 2008 R2 SSMS, the "Script Constraint as -> DROP And CREATE To" command produces T-SQL like below

USE [MyDatabase]
GO

IF  EXISTS (SELECT * FROM dbo.sysobjects WHERE id = OBJECT_ID(N'[DEF_Detail_IsDeleted]') AND type = 'D')
BEGIN
ALTER TABLE [Patient].[Detail] DROP CONSTRAINT [DEF_Detail_IsDeleted]
END

GO

USE [MyDatabase]
GO

ALTER TABLE [Patient].[Detail] ADD  CONSTRAINT [DEF_Detail_IsDeleted]  DEFAULT ((0)) FOR [IsDeleted]
GO

Out of the box, this script does NOT drop the constraint because the SELECT returns 0 rows. (see post Microsoft Connect).

The name of the default constraint is wrong but I gather it also has something to do with the OBJECT_ID function because changing the name doesn't fix the problem.

To fix this, I removed the usage of OBJECT_ID and used the default constraint name instead.

(SELECT * FROM dbo.sysobjects WHERE [name] = (N'DEF_Detail_IsDeleted') AND type = 'D')