Source:
ROWID is the pseudo column,which is unique for every row.Based on this rowid the record can be eliminated.
Query:
DELETE FROM DUP_DEL
WHERE ROWID
NOT IN
(
SELECT MAX(ROWID) FROM DUP_DEL GROUP BY EMPNO
);
This calculates the maximum ROWID and deletes the rows which are not in the maximum ROWID.
After Delete:
ROWID is the pseudo column,which is unique for every row.Based on this rowid the record can be eliminated.
Query:
DELETE FROM DUP_DEL
WHERE ROWID
NOT IN
(
SELECT MAX(ROWID) FROM DUP_DEL GROUP BY EMPNO
);
This calculates the maximum ROWID and deletes the rows which are not in the maximum ROWID.
After Delete:
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