 <p>I think this is not working because the columns returned by both select must have the same names, so please try this</p> <pre><code>SELECT "dba"."Room"."ID" ID, "dba"."Room"."RoomNumName" RoomNumName from "dba"."Room" WHERE DeptID = 8225 EXCEPT SELECT "dba"."vwResultInspection_iDashboards"."roomID" ID, "dba"."vwResultInspection_iDashboards"."RoomNumName" RoomNumName FROM "dba"."vwResultInspection_iDashboards" where "dba"."vwResultInspection_iDashboards"."ClosedDate" &gt; '2015-01-01' AND "dba"."vwResultInspection_iDashboards"."ClosedDate" &lt; '2015-01-31 23:59:59.000' and DEPTID = 8225 </code></pre>