Select distinct values from multiple columns

I had a table (Some_Table) with two columns:

A B

-------------------

1 test

2 test

3开发者_如何学C test1

4 test1

i would like to return DISTINCT values for column B and it's associated value in column A (first in distinct set), so something like this:

A B

-----------

1 test

3 test1

What is the sql?

select min(A),B
  from table
 group by B