USING ROWNUM

Question

Hi,
I have 4 tables ( 1 parent - 3 child). Reference is the primary key/FK in these tables. Two of the child tables have 1..1 mapping with the parent table and I have created a view called data_view that would have all the essential columns from the parent + 2 child tables.
One of the child table (WORKFLOW) holds a 1.. m relationship with the parent table.
Now I want to move data from the 4 tables to two history
tables . One history table has the structure just similar to the data_view and the other history table has the same set of columns as the workflow table.
I tried to code a logic where by I insert the first 1000 rows into the history tables and then delete the same from the base tables. I placed this in a loop and gave the exit criteria as SQL%NOTFOUND
After inserting the first 1000 rows into the history tables and deleting the same from the base tables, the loops exits during the second iteration with the error, primary key constraint in the history table violated.
Am I missing something. Your comments on this would be appreciated
FUNCTION MOV(p_date DATE)
RETURN NUMBER
AS
BEGIN
LOOP
INSERT INTO HIST (
column_names(SELECT
column_names
FROM
dATA_VIEW
WHERE
TE_DATE <= P_DATE
AND REFERENCE NOT IN (SELECT REFERENCE FROM WORKFLOW WHERE PROCESSING_TYPE IN ('K','E'))
AND ROWNUM < 1000 );
EXIT WHEN SQL%NOTFOUND;
INSERT INTO WORKFLOW_HIST
(column_names)
(SELECT
column_names
FROM WORKFLOW
WHERE REFERENCE IN (SELECT reference FROM DATA_VIEW WHERE TE_DATE <= P_DATE
AND REFERENCE NOT IN (SELECT REFERENCE FROM WORKFLOW WHERE PROCESSING_TYPE IN ('K','E'))
AND ROWNUM < 1000));
DELETE FROM BASE CASCADE
WHERE REFERENCE IN ( SELECT reference FROM DATA_VIEW
WHERE TE_DATE <= P_DATE
AND REFERENCE NOT IN (SELECT REFERENCE FROM WORKFLOW WHERE PROCESSING_TYPE IN ('K','E'))
AND ROWNUM < 1000);
COMMIT;
END LOOP;
RETURN 0;
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE(SQLERRM);
ROLLBACK;
RETURN SQLCODE;
END MOV;
thanks

Answer 1

Hi,
The problem is just beacuse of ROWNUM..
SELECT REFERENCE FROM WORKFLOW WHERE PROCESSING_TYPE IN ('K','E'))
AND ROWNUM < 1000 );
Instead try this statement...
SELECT REFERENCE FROM (Select Reference from WORKFLOW WHERE PROCESSING_TYPE IN ('K','E')
Order By Reference)
Where ROWNUM <= 1000;
Sol is if you use "order by" inside a subquery and then use ROWNUM, it should solve your problem.
My suggestion is plz dont rely on ROWNUM on these kind of operations. You can get unexpected results.
You can also use ROWNUMBER() instead of ROWNUM.
Thanks...