NVL(SUM(DECODE(SIGN(MMT.PRIMARY_QUANTITY), 1, 1, 0) * MMT.PRIMARY_QUANTITY),0) RECEIVED_QTY,
SELECT SIGN(3) FROM DUAL --符號函數 輸出1
SELECT SIGN(-100) FROM DUAL --符號函數 輸出-1
SELECT SIGN(0) FROM DUAL --符號函數 輸出0
DECODE(SIGN(MMT.PRIMARY_QUANTITY), 1, 1, 0)--SIGN()返回1 則輸出1 否則輸出0