FIRST DAY OF THE MONTH

SELECT TRUNC (SYSDATE, 'month') - 1, TRUNC (SYSDATE, 'month'),
LAST_DAY (SYSDATE)
FROM DUAL



SELECT TRUNC (doctdate)
FROM DUAL
WHERE TRUNC (:p11) BETWEEN TRUNC (:p12, 'month') AND TRUNC (:p12)


SELECT TRUNC (SYSDATE, 'month'), TRUNC (SYSDATE)
FROM DUAL