WHERE IS NULL Not Working in Nested Select - sql

Question

INSERT INTO AutomatedTest_XMLReconciliation(TaskID, TestCaseID, TestInstanceID, XMLHierarchyLevelID, XMLNode, XMLValue_Truth, XMLValue_Test)
(
(SELECT A.TaskID, A.TestCaseID, NULL, A.XMLHierarchyLevelID, A.XMLNode, A.XMLValue_Truth, NULL
FROM AutomatedTest_XMLTruthData A
LEFT JOIN AutomatedTest_Auth B
ON A.TestCaseID = B.TestCaseID
FULL Join AutomatedTest_XMLTestData C
ON B.TestInstanceID = C.TestInstanceID AND A.TruthIdentity = C.TestIdentity AND A.XMLHierarchyLevelID = C.XMLHierarchyLevelID AND A.XMLNode = C.XMLNode AND A.TaskID = C.TaskID
WHERE (B.ReconcileDate IS NULL AND A.TaskID IS NOT NULL)
EXCEPT
(Select A.TaskID, A.TestCaseID, NULL, A.XMLHierarchyLevelID, A.XMLNode, A.XMLValue_Truth, NULL
FROM AutomatedTest_XMLTruthData A
INNER JOIN AutomatedTest_Auth B
ON A.TestCaseID = B.TestCaseID
INNER JOIN AutomatedTest_XMLTestData C
ON B.TestInstanceID = C.TestInstanceID AND A.TruthIdentity = C.TestIdentity AND A.XMLHierarchyLevelID = C.XMLHierarchyLevelID AND A.XMLNode = C.XMLNode AND A.TaskID = C.TaskID)
)
UNION
(SELECT C.TaskID, NULL, C.TestInstanceID, C.XMLHierarchyLevelID, C.XMLNode, NULL, C.XMLValue_Test
FROM AutomatedTest_XMLTruthData A
LEFT JOIN AutomatedTest_Auth B
ON A.TestCaseID = B.TestCaseID
FULL JOIN AutomatedTest_XMLTestData C
ON B.TestInstanceID = C.TestInstanceID AND A.TruthIdentity = C.TestIdentity AND A.XMLHierarchyLevelID = C.XMLHierarchyLevelID AND A.XMLNode = C.XMLNode AND A.TaskID = C.TaskID
WHERE B.ReconcileDate IS NULL AND C.TaskID IS NOT NULL)
EXCEPT
(Select C.TaskID, NULL, C.TestInstanceID, C.XMLHierarchyLevelID, C.XMLNode, NULL, C.XMLValue_Test
FROM AutomatedTest_XMLTruthData A
INNER JOIN AutomatedTest_Auth B
ON A.TestCaseID = B.TestCaseID
INNER JOIN AutomatedTest_XMLTestData C
ON B.TestInstanceID = C.TestInstanceID AND A.TruthIdentity = C.TestIdentity AND A.XMLHierarchyLevelID = C.XMLHierarchyLevelID AND A.XMLNode = C.XMLNode AND A.TaskID = C.TaskID)
))
UPDATE AutomatedTest_Auth
SET ReconcileDate = GETDATE()
WHERE (TestCaseID IN (Select TestCaseID FROM AutomatedTest_DataReconciliation WHERE TestCaseID IS NOT NULL)
OR TestInstanceID IN (Select TestInstanceID FROM AutomatedTest_DataReconciliation WHERE TestInstanceID IS NOT NULL))
AND ReconcileDate IS NULL
So I've got this insert query that is meant to check two tables, one test and one auth, and compare their rows. It matches a TestInstance in the test table with a TestCase in a truth table through the AutomatedTest_Auth table.
Once it is done, it updates the AutomatedTest_Auth table with the GETDATE() stamp to show that the reconciliation process is complete. The insert checks this in the WHEREs to make sure that it does not insert anything that is already inserted by making sure the ReconcileDate IS NULL (it defaults to null on upon a new entry into the AutomatedTest_Auth table).
My problem, however, is that the second "B.Reconcile IS NULL" is not working. Upon running this twice, it will pick up the same rows from AutomatedTest_XMLTestData it picked up the first time and insert them again. (Just a note, there is no PK violation, as the Reconciliation columns could overlap at any time; it has an identity column instead).
Is this an order of operations issue? ... a bug? Any help would be nice.
Also, when I change the B.ReconcileDate IS NULL to IS NOT NULL, the insert swaps, and it will instead insert the same rows from AutomatedTest_XMLTruthData and not AutomatedTest_XMLTestData, so I know the inserts from AutomatedTest_XMLTruthData are correctly recognizing the WHERE clause, and that AutomatedTest_XMLTestData is incorrectly inverting the B.ReconcileData IS NULL to IS NOT NULL.

Answer 1

You are inserting into a table called AutomatedTest_XMLReconciliation
The update where condition looks at a table called AutomatedTest_DataReconciliation which is not referenced elsewhere in your script. Is this correct? I think the Update should be:
UPDATE AUTOMATEDTEST_AUTH
SET RECONCILEDATE = GETDATE()
WHERE ( TESTCASEID IN (SELECT TESTCASEID
FROM AUTOMATEDTEST_XMLRECONCILIATION
WHERE TESTCASEID IS NOT NULL)
OR TESTINSTANCEID IN (SELECT TESTINSTANCEID
FROM AUTOMATEDTEST_XMLRECONCILIATION
WHERE TESTINSTANCEID IS NOT NULL) )
AND RECONCILEDATE IS NULL