Statement below is working on Oracle 9i but not on Oracle 11g SELECT * FROM ( SELECT 0 scrnfail_rate, '9' zz, 7 hh FROM DUAL UNION ALL SELECT 0 scrnfail_rate, '9' zz, 7 hh FROM DUAL ) WHERE zz IS NOT NULL AND TO_CHAR (hh) NOT IN ( SELECT DECODE ( scrnfail_rate, 0, -1, ROUND (LEVEL * 1 / (scrnfail_rate / 100)) - ROUND (1 / (2 * (scrnfail_rate / 100))) ) AS nno FROM DUAL WHERE NVL (scrnfail_rate, 0) > 0 CONNECT BY LEVEL <= ROUND(9 * scrnfail_rate / 100) ) It looks like Oracle 11g is ignoring where decode or even where clause in the subquery. This query should return two rows as it does on Oracle 9i, but results ORA-01476: divisor is equal to zero on Oracle 11g EE 11.2.0.1.0 - 64bit. Can anyone help? Thanks!