这样一个sql语句，该如何优化呢？谢谢~~~解决立刻给分
SELECT
(SELECT COUNT(*) FROM table1 WHERE id1=1001) AS a1,
(SELECT COUNT(*) FROM table1 WHERE id2=2001) AS a2,
(SELECT COUNT(*) FROM table1 WHERE id1=1001 AND id2=2001) AS a3,
(SELECT SUM(num1) FROM table1 WHERE id1=1001) AS b1,
(SELECT SUM(num1) FROM table1 WHERE id2=2001) AS b2,
(SELECT SUM(num1) FROM table1 WHERE id1=1001 AND id2=2001) AS b3,
(SELECT SUM(num2) FROM table1 WHERE id1=1001) AS c1,
(SELECT SUM(num2) FROM table1 WHERE id2=2001) AS c2,
(SELECT SUM(num2) FROM table1 WHERE id1=1001 AND id2=2001) AS c3
这样就可以获得a1,a2,a3,b1,b2,b3,c1,c2,c3这9个值，有什么方法可以把这个sql语句进行优化么？就是让速度再快一些
给ID1和ID2建上索引。
呵呵,建立索引可以的
ps,有必要这样写sql嘛?可能对于写程序来讲可以只用写一次sql就把数据都读出来吧.个人觉得不好
首先sql语句优化如下，目的减少扫描次数。
SELECT
(SELECT COUNT(*) as a1, sum(num1) as b1, sum(num2) as c1 FROM table1 WHERE id1=1001)
(SELECT COUNT(*) as a2, sum(num1) as b2, sum(num2) as c2 FROM table1 WHERE id2=2001)
(SELECT COUNT(*) as a3, sum(num1) as b3, sum(num2) as c3 FROM table1 WHERE id1=1001 AND id2=2001) AS c3)
)
并且在表的id1, id2建立符合簇索引就可以了。
