Question : Subquery in Check constraint

SQL Server 7.0 is telling me that I can't do this:

CONSTRAINT my_check CHECK (ColumnName IN (SELECT SomeValue FROM ReferenceTable))

It tells me that subqueries are not allowed.  So then, how do I enforce this business rule at the database level?

Answer : Subquery in Check constraint

In that case, you MUST use triggers to enforce these rules:

CREATE TRIGGER
ON YourTable
FOR INSERT, UPDATE
IF UPDATE(ColumnName)
  IF EXISTS ( SELECT ColumnName FROM inserted LEFT JOIN SomeTable ON SomeTable.SomeField = inserted.ColumnName
  WHERE  
   AND SomeTable.SomeField IS NULL )
     BEGIN    
        ROLLBACK TRAN
        -- eventually RAISERROR ...
     END

Cheers