Question

Consider the following table:

  A  |  B
-----|------
 123 |  1
 456 |  2
 123 |  5
 456 |  0
 789 |  3
 789 |  9
 123 |  6

I want to get the following output:

  A  |  B
-----|------
 123 |  6
 456 |  2
 789 |  9

In other words: the greatest value of B for each equal value in A.

The initial table above comes already from another query which only selects duplicates of A:

select A, B from tbl where A in (
  select A from tbl
  group by A
  having count(A) > 1
);

I tried wrapping/integrating another grouping function with and without max(B) around/into this query, but no success.

How can I get the desired output?

Answer 1

Just use max:

  select A, max(B) 
  from tbl
  group by A
  having count(A) > 1