SELECT only one row in the case where there are multiple values for a particular column

Question

I have a simple 2-column table, where both columns are integers:

3;1
1;2
2;1

Let's call the columns 'a' and 'b', respectively. Please notice that two rows have the value 1 for column b.

What SQL query would allow me to get all rows in this table, but only one row (no preference - 1;1 or 2;1) when there are multiple rows with the same value in the column b?

In other words either of these resultsets is fine:

3;1
1;2

OR

1;2
2;1

because we have exactly 1 row for any particular value of b.

Answer 1

SELECT MAX(A) AS A, B
FROM TABLE
GROUP BY B;

Note that it would work equally with MIN, FIRST or LAST