Today I hava a question when I add an index on table DST
SELECT * FROM DST WHERE MON='2002-12-1' and ( DST_NO='' OR DST_USER_NO='20000629' )
CAN GET RIGHT RESULTS.

SELECT * FROM DST WHERE MON='2002-12-1' and ( DST_NO='' OR
DST_USER_NO='20000629' ) and BUS_CODE='D'
NO RESULTS.

SELECT * FROM DST WHERE MON='2002-12-1' and ( DST_NO='' OR DST_USER_NO='20000629' ) and BUS_CODE='D' and DST_USER_NO='20000629'
CAN GET RIGHT RESULTS.

When I change the lock type from PAGE to TABLE
All rights are right.

Can You tell me why,thanks