MS Access SQL: Aggregating on Min Value but retrieving other fields

问题

This may be an extremely easy question but I can't get my head around how to solve it in MS Access. It has probably been answered before but I haven't been able to find it.

I have a table with 3 columns: col1 is an object ID, col2 and col3 are measurements. I've built a query so that for each object we get the corresponding minimum value in col2. This works OK with a simple group-by query. The problem is when I try to pull col3 (associated with the row where minimum value was found), it will no longer group-by properly.

I've been playing with the group-by clause and tried to divide into several queries but so far no luck.

Here's an example of what I have (left) and would like to get (right):

col1  col2  col3   --->   col1  minC2 col3 
----  ----  ----          ----  ----  ----
1     0     1.8           1     0     1.8   
1     1     1.4           2     2     2.5
2     4     1.1           3     1     7.6
2     6     4.7
2     2     2.5
3     4     3.3
3     1     7.6

I hope this makes sense. Any help/MS Access SQL syntax is appreciated... Thanks!

回答1:

Assuming that the second line of what you like to get is [2 2 2.5], this is what you're looking for:

select a.col1, a.colm, m.col3
from
    (
        select col1, min(col2) as colm
        from test
        group by col1
    ) as a
inner join test m on a.col1 = m.col1 and a.colm = m.col2

回答2:

You can use a subquery:

select t.col1, tt.col2 , tt.col3
from (
      SELECT col1, Min(col2) AS mcol2
      FROM Tmp
      group by col1) t,  tmp tt
where t.col1 =  tt.col1 and t.mcol2 = tt.col2

来源：https://stackoverflow.com/questions/11063408/ms-access-sql-aggregating-on-min-value-but-retrieving-other-fields