first minimum date in the column for each distinct column a value

[rajesh]

Hi ,

i want to select the first minimum date in the column d for each
distinct column a value.
how i can do that in a sql query.

xyztable

Column a Column b Column c Column d

6014350 -10 2008-02-22 00:00:00 2008-02-12 00:00:00
6014350 4 2008-02-22 00:00:00 2008-02-26 00:00:00
6014472 -7 2008-03-06 00:00:00 2008-02-28 00:00:00
6014472 32 2008-03-06 00:00:00 2008-04-07 00:00:00

i need the results like this....

Column a Column b Column c Column d
6014350 -10 2008-02-22 00:00:00 2008-02-12 00:00:00
6014472 -7 2008-03-06 00:00:00 2008-02-28 00:00:00

Thanks
Rajesh kumar