SQL union grouped by rows

Assume I have a table like this:

col1	col2	col3	col4
commonrow	one	two	null
commonrow	null	null	three

How to produce a result to look like this:

col1	col2	col3	col4
commonrow	one	two	three

Thanks

Answer

like this, you can group by col1 and get the maximum in each group:

select col1 , max(col2) col2 , max(col3) col3 , max(col4) col4
from table 
group by col1