在 MySQL 中使用 MAX() 过滤两次

Question

I have the following table called my_values in a MySQL 5.7 database:

value1	value2	value3
foo	7	something4
foo	5	something1
foo	12	anything5
bar	3	something7
bar	18	anything5
bar	0	anything8
baz	99	anything9
baz	100	something0

As you see, there are duplicates in value1 . I want to SELECT each unique value1 only once, but that row with the highest value in value2 .

I'm using this query for that:

SELECT v.* FROM my_values v WHERE v.value2 = (SELECT MAX(v2.value2) FROM my_values v2 WHERE v2.value1 = v.value1);

The result is:

value1	value2	value3
foo	12	anything5
bar	18	anything5
baz	100	something0

Here's a fiddle of that.

From this result I want to SELECT each unique value3 only once, but that row with the highest value in value2 (no matter what value1 is).

So expected result would be:

value1	value2	value3
bar	18	anything5
baz	100	something0

How can I do that?

Answer 1

here is how you can do it:

select t1.*
from my_values t1
natural join (select value1, MAX(value2) value2
               from my_values 
               group by value1 ) t2
natural join (select value3, MAX(value2) value2
               from my_values 
               group by value3) t3

fiddle

Answer 2

You can use tuples for the comparison:

select t.*
from my_values t
where (t.value2, t.value3) = (select t2.value2, t2.value3
                              from my_values t2
                              where t2.value1 = t.value1
                              order by t2.value2 desc, t2.value3 desc
                              limit 1
                             );