@dmitriy said:My function has the output backwards, here is the corrected version.CREATE FUNCTION dbo.IsClientNew (@ClientTypeID INT, @ClientNumber AS VARCHAR(50))  RETURNS INTAS  BEGINSELECT (1 - count( dbo.Client.ClientID )) AS ExistsFROM dbo.ClientWHERE dbo.Client.ClientTypeID = @ClientTypeID AND dbo.Client.ClientNumber = @ClientNumberENDYes, ClientID is unique for a give type and number. How about this:CREATE FUNCTION dbo.IsClientNew (@ClientTypeID INT, @ClientNumber AS VARCHAR(50))  RETURNS INTAS  BEGINRETURN ISNULL((SELECT 0 FROM dbo.Client WHERE dbo.Client.ClientTypeID = @ClientTypeID AND dbo.Client.ClientNumber = @ClientNumber), 1)END