SELECT COL1, COL2, DATECOL
FROM TABLE
WHERE DATECOL >= ADD_MONTHS (CURRENT_DATE -EXTRACT(DAY FROM CURRENT_DATE) + 1 , -1)
AND DATECOL < CURRENT_DATE -EXTRACT(DAY FROM CURRENT_DATE) + 1
or you might just want to enter date
>=DATE '2014-05-01'
< DATE '2014-04-01'