Question

Could you please help me in simplifying and reducing the cost of the below query?

I tried making it a co-related subquery with NOT EXISTS but it didn’t give me any output.

Please note that the table in both main and inner query is the same ‘table_1″.

SELECT *
FROM Table_1 A
WHERE A.Col1              = 'abcd'
AND (A.Col2, A.Col3) NOT IN
  (SELECT Col2,
    Col3
  FROM Table_1 B
  WHERE (B.Col4 IN (1,2,3)
  And B.Col5    In ('x','y'))
  OR (B.Col4     = 1 AND B.Col5     = 'z' AND B.Col6     = 'f')
  ))

Thanks in advance,
Savitha

Answer 1

Usually its a lot about trial and error. In addition to using the not exists and outer join, since this is a self-join, it should reduce down to a single table…

SELECT *
FROM Table_1
WHERE col1 = 'abcd'
AND NOT
   (col4 IN (1,2,3)
      AND col5 IN ('x','y')
)
AND NOT (col4=1
  AND col5='z'
  AND col6='f'
);

Or you could try using a MINUS…

SELECT *
FROM Table_1
WHERE col1 = 'abcd'
MINUS
SELECT *
FROM Table_1
WHERE col1 = 'abcd'
AND ((col4 IN (1,2,3)
      AND col5 IN ('x','y'))
   OR (col4=1
      AND col5='z'
      AND col6='f')  
);

The most efficient solution will depend on the spread of the data.

but it didn’t give me any output

Are you sure there are matching rows?