有三个表A,B,C相同结构如下:
Time,Data
如:
A B C
Time Data Time Data Time Data
08:59 12 07:59 1 08:59 23
09:00 13 09:00 2 11:00 25
10:01 15 11:00 3 12:00 26
以时间排列,组合数据如下:
Time A_Data B_Data C_Data
07:59 1
08:59 12 23
09:00 13 2
10:01 15
11:00 3 25
12:00 26
sql 最后精简一些,运行速度快一点,非常感谢,这贴限制最多只能给100分,分不够说一声,我另开贴加分。
非常感谢。
树哥的回复如下,但是表多或者数据量大的时候就相当的慢了,不知道还有没有更快一点的方法?
- SQL code
select isnull(isnull(a.time,b.time),c.time) as time,a.data,b.data,c.datafrom afull join b on a.time=b.timefull join c on a.time=c.time or b.time=c.timeorder by 1/**time data data data----- ----------- ----------- -----------07:59 NULL 1 NULL08:59 12 NULL 2309:00 13 2 NULL10:01 15 NULL NULL11:00 NULL 3 2512:00 NULL NULL 26(6 行受影响)**/
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树哥的这个已经比较简单了 你可以在a,b,c表的time字段加索引。
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- SQL code
只有索引了CREATE INDEX time_index ON A(time)CREATE INDEX time_index ON B(time)CREATE INDEX time_index ON C(time)
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2000数据库不能用with的
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- SQL code
--创建一个索引视图create view v1asselect time from aunionselect time from bunionselect time from cgo--按视图查询select t.time,a.data as A_data,b.data as B_data,c.data as C_datafrom v1 t left join a on t.time = a.time left join b on t.time = b.time left join c on t.time = c.time
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- SQL code
SELECT TIME ,SUM(A_DATA) AS A_DATA ,SUM(B_DATA) AS B_DATA ,SUM(C_DATA) AS C_DATAFROM (SELECT TIME ,DATA AS A_DATA,CAST(NULL AS INT) AS B_DATA,CAST(NULL AS INT) AS C_DATAFROM AUNION ALLSELECT TIME ,NULL AS A_DATA,DATA AS B_DATA,CAST(NULL AS INT) AS C_DATAFROM BUNION ALLSELECT TIME ,NULL AS A_DATA,NULL AS B_DATA,DATA AS C_DATAFROM C) AS TGROUP BY TIME
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那用with表达式也是一样的吧
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你的是用2000的只有用view来做了