将两列按功能SQL分组

Question

If I have the below select query:

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

How to add col6 = col4/col5?

Answer 1

You cannot access the alias in the SELECT clause. So you have to repeat 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 2

Do the GROUP BY in a derived table:

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

Answer 3

You can perform operations in the select statement. However, you cannot use the aliases of the SQL statement within it. So you need to do the calculation for col4 again. Just add 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