sql server 这个循环为什么这么慢数据也不大（在线）

DECLARE @id INT,
@maxid INT
SET @id=1
SELECt @maxid = Max(rownum)
FROM (SELECt *
FROM (SELECt Row_number()
OVER(
ORDER BY parent) AS rownum,
t.*
FROM (SELECt DISTINCT parent,
qushu
FROM A_RAZ t
WHERe EXISTS (SELECt 1
FROM member
WHERe CONVERT(VARCHAr(100), register_on, 23) = @v_date
AND member_num = t.member))t)a)b
WHILE @id <= @maxid
BEGIN
DECLARE @parent NVARCHAr(50),
@qushu INT
WITH temp
AS (SELECt Row_number()
OVER(
ORDER BY parent) AS rownum,
t.parent,
t.qushu
FROM (SELECt DISTINCT parent,
qushu
FROM A_RAZ t
WHERe EXISTS (SELECt 1
FROM member
WHERe CONVERT(VARCHAr(100), register_on, 23) = @v_date
AND member_num = t.member))t)
SELECt @parent=parent,@qushu=qushu
FROM temp
WHERe rownum = @id
IF @qushu = 1
BEGIN
DECLARE @left_a INT,
@left_b INT
SELECt @left_a = Isnull(Max(plvl), 0)
FROM A_RAZ t

SELECt @left_b = Isnull(Max(plvl), 0)
FROM A_RAZ t

IF @left_b > @left_a
BEGIN
INSERT INTO t_member_ceng
(partent,
ceng_a)
VALUES (@parent,
@left_b - @left_a)
END
END

思路：
1、优化现有SQL语句
2、依据SQL语句中的条件增加相应类型的索引
3、可以使用临时表加速数据的处理
原则上来说，你要找到是因为IO消耗大，还是CPU消耗高，找到原因，才能对症下药

使用附带安装的vs跟踪调试