BUG: Error 221 Fetching from Keyset Cursor Using Outer Join

• Microsoft SQL Server Programmer's Toolkit, version 4.2

SYMPTOMS

When calling DB-Library function dbcursorfetch(), the function call fails, generating error 221:

   Column of type (%s) does not allow nulls. It may not be compared
   with null.

CAUSE

This problem occurs when fetching from a keyset driven cursor opened based on a query containing an outer join. This problem appears only in DB- Library version 4.20.50 and later. When building the query to perform the cursor fetch, DB-Library is incorrectly attempting to compare a NOT NULL column with the value NULL.

WORKAROUND

Dynamic and Forward scrolling cursors do not exhibit this problem and may be used successfully with outer joins. If keyset driven cursors must be used, DB-Library version 4.20.21 and earlier can be used to successfully fetch from a keyset driven cursor opened with an outer join.

STATUS

Microsoft has confirmed this to be a problem in DB-Library version 4.20.50. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.