[英]Is combining (result sets) of “two queries with aggregate and group by” possible?
1
Select id,count(*) as totalX FROM my_table WHERE x_factor = 1 GROUP BY id
结果集 :
id totalX
--------- --------------
9 34
10 6
11 21
12 3
2
Select id,count(*) as totalY FROM my_table WHERE y_factor = 1 GROUP BY id
结果集2:
id totalY
--------- --------------
9 334
10 56
11 251
12 93
有没有办法我可以做到这一点:
id totalX totalY
--------- -------------- --------------
9 34 334
10 6 56
11 21 251
12 3 93
我想在RHEL 5上使用Sybase 12.5的解决方案,我也想知道在其他任何数据库系统中是否可行。
---谢谢您的回答-
Comparing EXECUTION TIME: (For a certain query)
Query 1:
Execution Time 61.
SQL Server cpu time: 6100 ms. SQL Server elapsed time: 12133 ms.
Query 2:
Execution Time 53.
SQL Server cpu time: 5300 ms. SQL Server elapsed time: 12090 ms.
Query X(1+2):
Execution Time 84.
SQL Server cpu time: 8400 ms. SQL Server elapsed time: 21456 ms.
通过对列使用CASE / WHEN并基于true / false求和1或0,您可以在同一查询中获得两者。此外,如果希望将另一个值的总和作为另一个,则可以执行相同的操作列...只需将其替换为真实值即可,而不是1。
select
id,
sum( CASE WHEN x_factor = 1 THEN 1 ELSE 0 END ) as X_Count,
sum( CASE WHEN y_factor = 1 THEN 1 ELSE 0 END ) as Y_Count
from
yourTable
group by
id
这应该工作:
SELECT id,
sum(case when x_factor = 1 then 1 else 0 end) as totalX,
sum(case when y_factor = 1 then 1 else 0 end) as totalY
FROM my_table
WHERE x_factor = 1
OR y_factor = 1
GROUP BY id
CASE ... {0 | 1}对于人们来说是个不错的窍门,但我认为问题可能比这更简单。 你有没有尝试过:
SELECT id, COUNT(x_factor) AS count_x, COUNT(y_factor) AS count_y FROM my_table GROUP BY id
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