mysql - 优化一个 SQL 查询

Question

我需要运行查询以从数据库中获取一些数据。问题是我使用的查询有效但需要很长时间。

SELECT SHH1.CUST_NO,
       SHH1.CUST_NAME,
       ADDR.BVADDREMAIL 
FROM SALES_HISTORY_HEADER SHH1
INNER JOIN ADDRESS ADDR ON (SHH1.CUST_NO=ADDR.CEV_NO)
INNER JOIN CUSTOMER CUST ON (SHH1.CUST_NO=CUST.CUS_NO)
WHERE CUST.HOLD = 0
AND SHH1.CUST_NO IN (SELECT SHH2.CUST_NO 
                     FROM SALES_HISTORY_HEADER SHH2
                     GROUP BY SHH2.CUST_NO 
                     HAVING Max(SHH2.IN_DATE) < '20120101')
GROUP BY SHH1.CUST_NO,
         SHH1.CUST_NAME,
         ADDR.BVADDREMAIL

我不是很擅长这个所以想知道你们中的任何人是否可以帮助我？谢谢。

Answer 1

我认为您不需要子选择。以下应该给你相同的结果:

SELECT SHH1.CUST_NO,SHH1.CUST_NAME,ADDR.BVADDREMAIL 
FROM SALES_HISTORY_HEADER SHH1
INNER JOIN ADDRESS ADDR ON (SHH1.CUST_NO=ADDR.CEV_NO)
INNER JOIN CUSTOMER CUST ON (SHH1.CUST_NO=CUST.CUS_NO)
WHERE CUST.HOLD = 0
GROUP BY SHH1.CUST_NO,SHH1.CUST_NAME,ADDR.BVADDREMAIL
HAVING Max(SHH1.IN_DATE) < '20120101'