select only the first row in a group

[wbooster]

If I have data

a 1
a 2
a 3
b 3
b 2
c 1
c 2
d 2

I only want to select a, b, c, and d's first record.like
a 1
b 3
c 1
d 2

how do I do it

 

[rtmpxr]

Maybe this is convenient:

select <col1>, min(<col2>) from <table> group by <col1>

Results:
a 1
b 2
c 1
d 2