Help Required in full outer Join

Question

I feel the below query can be changed to full outer join. But, I've not been able to do so.
I require your help in changing it to full outer join. My current query is
SELECT CLAIMNO,'1' INDX FROM D_CLAIM@CMS2PROD
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null
MINUS
SELECT CLAIMNO,'1' FROM D_CLAIM
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null
UNION
SELECT CLAIMNO,'2' FROM D_CLAIM
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null
MINUS
SELECT CLAIMNO,'2' FROM D_CLAIM@cms2prod
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null

Answer 1

donisback wrote:
I feel the below query can be changed to full outer join. But, I've not been able to do so.
I require your help in changing it to full outer join. My current query is
SELECT CLAIMNO,'1' INDX FROM D_CLAIM@CMS2PROD
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null
MINUS
SELECT CLAIMNO,'1' FROM D_CLAIM
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null
UNION
SELECT CLAIMNO,'2' FROM D_CLAIM
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null
MINUS
SELECT CLAIMNO,'2' FROM D_CLAIM@cms2prod
WHERE clntsys=76500 and facility=76501 and filecreatedt='18-feb-2011' and fileupdatedt is null
I do not think that query is doing what you think that it is doing - on first inspection, it was not doing what I thought either due to the order in which the UNION and MINUS operators are performed. If the FILECREATEDT column is defined as a DATE, your query is relying on an implicit date conversion - in such a case, you should replace:
filecreatedt='18-feb-2011'With:
filecreatedt=TO_DATE('18-feb-2011','DD-MON-YYYY')Now, building a simple model to explain what is happening, we create two tables with 10 rows each. The first table has C1 values that increase by 2, while the second has C1 values that increase by 3:
CREATE TABLE T1 AS
SELECT
  ROWNUM*2 C1,
  TRUNC(SYSDATE)+ROWNUM*2 C2
FROM
  DUAL
CONNECT BY
  LEVEL<=10;
CREATE TABLE T2 AS
SELECT
  ROWNUM*3 C1,
  TRUNC(SYSDATE)+ROWNUM*3 C2
FROM
  DUAL
CONNECT BY
  LEVEL<=10;It appears that the intended result of your query is to obtain a distinct list of those rows that are in each table that are not in both tables - the UNION ALL minus the intersection of the rows in two tables. However, that is not what you are achieving with that query. To demonstrate, the two halves of your query:
SELECT
  C1,
  C2
FROM
  T1
MINUS
SELECT
  C1,
  C2
FROM
  T2;
C1 C2
2 28-FEB-11
4 02-MAR-11
8 06-MAR-11
10 08-MAR-11
14 12-MAR-11
16 14-MAR-11
20 18-MAR-11
SELECT
  C1,
  C2
FROM
  T2
MINUS
SELECT
  C1,
  C2
FROM
  T1;
C1 C2
3 01-MAR-11
9 07-MAR-11
15 13-MAR-11
21 19-MAR-11
24 22-MAR-11
27 25-MAR-11
30 28-MAR-11As can be seen by the above, each half returned 7 rows - there are 7 rows in each table that is not in the other table. Common sense would state that if we UNION these two results (assuming no duplicate values in each table), we would see 14 rows:
SELECT
  C1,
  C2
FROM
  T1
MINUS
SELECT
  C1,
  C2
FROM
  T2
UNION
SELECT
  C1,
  C2
FROM
  T2
MINUS
SELECT
  C1,
  C2
FROM
  T1;
C1 C2
3 01-MAR-11
9 07-MAR-11
15 13-MAR-11
21 19-MAR-11
24 22-MAR-11
27 25-MAR-11
30 28-MAR-11Only 7 rows? Let's try again with the help of inline views to control the order in which the MINUS and UNION operators are processed:
SELECT
FROM
  (SELECT
    C1,
    C2
  FROM
    T1
  MINUS
  SELECT
    C1,
    C2
  FROM
    T2)
UNION
SELECT
FROM
  (SELECT
    C1,
    C2
  FROM
    T2
  MINUS
  SELECT
    C1,
    C2
  FROM
    T1);
C1 C2
2 28-FEB-11
3 01-MAR-11
4 02-MAR-11
8 06-MAR-11
9 07-MAR-11
10 08-MAR-11
14 12-MAR-11
15 13-MAR-11
16 14-MAR-11
20 18-MAR-11
21 19-MAR-11
24 22-MAR-11
27 25-MAR-11
30 28-MAR-11Note that the above returned 14 rows. We can do the same using just two outer joins:
SELECT
  T1.C1,
  T1.C2
FROM
  T1,
  T2
WHERE
  T1.C1=T2.C1(+)
  AND T2.C1 IS NULL
UNION
SELECT
  T2.C1,
  T2.C2
FROM
  T1,
  T2
WHERE
  T2.C1=T1.C1(+)
  AND T1.C1 IS NULL;
C1 C2
2 28-FEB-11
3 01-MAR-11
4 02-MAR-11
8 06-MAR-11
9 07-MAR-11
10 08-MAR-11
14 12-MAR-11
15 13-MAR-11
16 14-MAR-11
20 18-MAR-11
21 19-MAR-11
24 22-MAR-11
27 25-MAR-11
30 28-MAR-11Or we can do it with a full outer join and a MINUS operator:
SELECT
  NVL(T1.C1,T2.C1) C1,
  NVL2(T1.C1,T1.C2,T2.C2) C2
FROM
  T1 FULL OUTER JOIN T2
    ON T1.C1=T2.C1
MINUS
SELECT
  T1.C1,
  T1.C2
FROM
  T1,
  T2
WHERE
  T1.C1=T2.C1;
C1 C2
2 28-FEB-11
3 01-MAR-11
4 02-MAR-11
8 06-MAR-11
9 07-MAR-11
10 08-MAR-11
14 12-MAR-11
15 13-MAR-11
16 14-MAR-11
20 18-MAR-11
21 19-MAR-11
24 22-MAR-11
27 25-MAR-11
30 28-MAR-11Or just with a full outer join with a WHERE clause:
SELECT
  NVL(T1.C1,T2.C1) C1,
  NVL2(T1.C1,T1.C2,T2.C2) C2
FROM
  T1 FULL OUTER JOIN T2
    ON T1.C1=T2.C1
WHERE
  (T1.C1 IS NULL
    OR T2.C1 IS NULL);
C1 C2
3 01-MAR-11
9 07-MAR-11
15 13-MAR-11
21 19-MAR-11
24 22-MAR-11
27 25-MAR-11
30 28-MAR-11
8 06-MAR-11
20 18-MAR-11
2 28-FEB-11
10 08-MAR-11
4 02-MAR-11
14 12-MAR-11
16 14-MAR-11With the above knowledge, you should be able to fix your SQL statement to produce the expected results.
Charles Hooper
Co-author of "Expert Oracle Practices: Oracle Database Administration from the Oak Table"
http://hoopercharles.wordpress.com/
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.