标量子查询改写
SELECT A.CONS_NO,
A.CONS_NAME,
(SELECT SUM(T.PURCH_PQ)
FROMGAS_CA.A_CARD_METER_PAY T
WHERE CONS_NO = A.CONS_NO
AND T.PURCH_GAS_TIME > TO_DATE('20160229', 'YYYYMMDD')) 购气量
FROM GAS_MB.C_CONS A
WHERE A.ORG_NO LIKE '1125%'
AND EXISTS
(SELECT 1
FROM GAS_MB.C_MP B
WHERE B.CONS_ID = A.CONS_ID
AND EXISTS
(SELECT 1
FROM GAS_MB.C_METER
WHERE MP_ID = B.MP_ID
AND PRODUCE_FACT IN ('0010', '0015', '0024')));
在子查询的数量比较大的时候查询效率会比较低下，这里用表连接的方式改写一下
SELECT *
FROM (SELECT A.CONS_NO, A.CONS_NAME, B.购气量
FROM GAS_MB.C_CONS A,
(SELECT B1.CONS_NO, SUM(B1.PURCH_PQ) 购气量
FROMGAS_CA.A_CARD_METER_PAY B1
WHERE B1.ORG_NO LIKE '1125%'
AND B1.PURCH_GAS_TIME > TO_DATE('20160229', 'YYYYMMDD')
GROUP BY B1.CONS_NO) B
WHERE A.ORG_NO LIKE '1125%'
AND A.CONS_NO = B.CONS_NO(+)
AND EXISTS
(SELECT 1
FROM GAS_MB.C_MP B
WHERE B.CONS_ID = A.CONS_ID
AND EXISTS
(SELECT 1
FROM GAS_MB.C_METER
WHERE MP_ID = B.MP_ID
AND PRODUCE_FACT IN ('0010', '0015', '0024'))))
WHERE 购气量 IS NOT NULL;