help with a simple query

I need to do a following query (using table a, b):

select *
from a
where a.col1=val1 or if a.col1=null then b.col1=val1

                      wherea.col2 = b.col2

how to express the if part using SQL? thanks a lot!

(basically what I want to do is: selection based tableA column1, but if tableA column1 is null, join tableA with tableB using column2 and make sure tableB column 1 equal to the input value)

Thanks!

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http://www.deja.com/ Received on Mon Dec 18 2000 - 15:46:39 CST