将两列按功能分组SQL

Question

如果我有以下 select 查询：

select col1, col2, col3, sum(value1) as col4, col5
from table1
group by col1, col2, col3, col5

如何添加col6 = col4/col5?

Answer 1

您可以在select 语句中执行操作。但是，您不能在其中使用 SQL 语句的别名。因此，您需要再次对 col4 进行计算。只需添加 sum(value1)/col5 as col6.

select col1, col2, col3, sum(value1) as col4, col5, sum(value1)/col5 as col6
from table1
group by col1, col2, col3, col5

Answer 2

您无法访问 SELECT 子句中的别名。所以你必须重复 sum(value1):

select col1, col2, col3, 
       sum(value1) as col4, 
       col5, 
       sum(value1) / col5 as col6
from table1
group by col1, col2, col3, col5

Answer 3

在派生的 table 中执行 GROUP BY:

select col1, col2, col3, col4, col5, col4/col5 as col6 
from
(
    select col1, col2, col3, sum(value1) as col4, col5
    from table1
    group by col1, col2, col3, col5
) dt

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