Question

I am using SQL Server 2005 and in one of the tables i have a column that stores stored proc name. While inserting values in that column I want to ensure that a stored proc of that name exists in the database.

ALTER TABLE MyTable WITH CHECK 
   ADD CONSTRAINT [CK_MyTable_MyColumn] CHECK ((SELECT COUNT(*)  FROM sys.sysobjects WHERE id = object_id(MyColumn) AND OBJECTPROPERTY(id, N'IsProcedure')=1) = 1)

but this gives the following error

Subqueries are not allowed in this
context. Only scalar expressions are
allowed.

How can I do this.

Answer 1

Functions are allowed:

create function dbo.IsProcedure(@ProcName sysname) returns bit as
return (SELECT COUNT(*) FROM sys.sysobjects 
  where id = object_id(MyColumn) and OBJECTPROPERTY(id, N'IsProcedure')=1);
go

ALTER TABLE MyTable WITH CHECK ADD CONSTRAINT [CK_MyTable_MyColumn]
CHECK (dbo.IsProcedure(MyColumn) = 1);