Full Outer Join based off multiple fields

Question

Here is the situation that I'm facing:

I have two tables A and B. If records are in table A and not in table B they need to be added to table B. If records are in table B and not in table A, then they need to be removed out of table B. The trick here is that it is the mixture of two keys that makes the unique combination

Table A    
Operation_Key    Part_Key  
1                1
1                2
2                1
2                3

Table B
Operation_Key    Part_Key  Record_Key
1                1         1
2                1         2
2                3         3
2                4         4

I am trying to get the right type of query so that the results returned look like

Results
Operation_Key        Part_Key  Record_Key   Action
1                    2         NULL         Add
2                    4         4            Delete

The query I have so far looks like similar to this:

CREATE TABLE #Action_Table
(
  Action VARCHAR(6),
  Action_Bit INT,
  Operation_Key INT,
  Record_Key INT,
  Part_Key INT
)
INSERT INTO #Action_Table
SELECT 
  CASE
    WHEN WS.Operation_Key IS NULL THEN 'Delete'
    WHEN WS.Operation_Key IS NOT NULL THEN 'Add'
  END Action,
  CASE
    WHEN WS.Operation_Key IS NULL THEN '0'
    WHEN WS.Operation_Key IS NOT NULL THEN '1'
  END Action_Bit,
  CASE
    WHEN WS.Operation_Key IS NULL THEN WC.Operation_Key
    WHEN WS.Operation_Key IS NOT NULL THEN WS.Operation_Key
  END Operation_Key,
  CASE
    WHEN WS.Operation_Key IS NULL THEN WC.Record_Key
    WHEN WS.Operation_Key IS NOT NULL THEN NULL
  END Workcenter_Component_Key,
  CASE
    WHEN WS.Operation_Key IS NULL THEN WC.Part_Key
    WHEN WS.Operation_Key IS NOT NULL THEN WS.Part_Key
  END Part_Key
FROM #WS_Part_Table WS
FULL OUTER JOIN #WC_Part_Table WC
  ON WC.Part_Key = WS.Part_Key
 AND WC.Operation_Key = WS.Operation_Key
WHERE (WS.Part_Key IS NULL or WC.Part_Key IS NULL) AND (WS.Operation_Key IS NULL or WC.Operation_Key IS NULL)

Both the #WS_Part_Table and the #WC_Part_Table are temp tables that I'm constructing using queries, but my dilemma is that I have to PRE-QUERY the #WC_Part_Table query on the operation key that I'm interested in, otherwise I get way too many results.

This is the query that I'm using to create the #WC_Part_Table

    CREATE TABLE #WC_Part_Table
    (
      Operation_Key INT,
      Record_Key INT,
      Part_Key INT
    )
    -- Workcenter Component Table
    INSERT INTO #WC_Part_Table
    SELECT
      O.Operation_Key,
      WC.Record_Key,
      WC.Part_Key
    FROM Workcenter_Component WC
    JOIN Operation O
      ON O.Default_Workcenter_Key = WC.Workcenter_Key

 /* There is some reason why this next line is needed */
    WHERE O.Operation_Key = 23149

Solution 1

Tyr this to get the results that you have posted:

SELECT COALESCE(a.Operation_Key, b.Operation_Key) Operation_Key,
             COALESCE(a.Part_Key, b.Part_Key) Part_Key,
             Record_Key,
             CASE 
                WHEN Record_Key IS NULL THEN 'Add'
                ELSE 'Delete'
            END Action
  FROM TableA a FULL OUTER JOIN TableB b
      ON a.Operation_Key = b.Operation_Key
        AND a.Part_Key = b.Part_Key
 WHERE (a.Operation_Key IS NULL) OR (b.Operation_Key IS NULL)

Test Script:

CREATE TABLE #TableA     
(       
    Operation_Key INT,       
    Part_Key INT
) 

INSERT INTO #TableA
SELECT 1,1 
UNION
SELECT 1,2 
UNION
SELECT 2,1 
UNION
SELECT 2,3 

CREATE TABLE #TableB
(       
    Operation_Key INT,       
    Part_Key INT,
    Record_Key INT
) 

INSERT INTO #TableB
SELECT 1,1,1 
UNION
SELECT  2,1,2
UNION
SELECT 2,3,3 
UNION
SELECT 2,4,4 


SELECT  COALESCE(a.Operation_Key, b.Operation_Key) Operation_Key,              
                COALESCE(a.Part_Key, b.Part_Key) Part_Key,              
                Record_Key,              
                CASE                  
                    WHEN Record_Key IS NULL THEN 'Add'                 
                    ELSE 'Delete'             
                END Action   
    FROM    #TableA a FULL OUTER JOIN #TableB b       
        ON  a.Operation_Key = b.Operation_Key         
     AND    a.Part_Key = b.Part_Key  
 WHERE (a.Operation_Key IS NULL) OR (b.Operation_Key IS NULL) 

Output:

Operation_Key   Part_Key    Record_Key  Action
1   2   NULL    Add
2   4   4   Delete

Solution 2

Add to B:

insert into B (Operation_Key, Part_Key, Record_Key)
values
select Operation_Key, Part_Key, null as Record_Key from A
left join b on a.Operation_Key = b.Operation_Key and
a.Part_Key = b.Part_Key
where b.Part_Key is null

Delete from B:

Delete from B
select * from B left join A on b.Operation_Key = a.Operation_Key and
    b.Part_Key = a.Part_Key
where a.Operation_Key is null

Solution 3

You can get exactly the results table you want (looking at your example set up) by making clever use of the SQL "COALESCE" operator. If you use a query like this:

SELECT
    COALESCE(A.Operation_Key, B.Operation_Key) as Operation_Key,
    COALESCE(A.part_key, B.part_key) as Part_Key,
    B.Record_Key,
    CASE WHEN A.Operation_Key IS NULL THEN
        'Delete'
    ELSE
        'Add'
    END AS [Action] FROM A
FULL OUTER JOIN B 
    ON A.Operation_Key = B.Operation_Key 
        AND A.Part_Key= B.Part_Key
WHERE A.Operation_Key IS NULL 
    OR B.Operation_Key IS NULL

...you'll get a result table exactly like your example.