best way to conditionally insert a row

I would like to insert a row into a table, but only if the primary key does not exist.

For example, if I have a table "keywords" with columns "name" and "val", I would like

   insert into keywords (name, val) values ('color', 'blue');

to happen only if there is not already a row where name='color'.

What is the best way to do this?

Many TIA!
Mark Received on Wed Aug 08 2007 - 19:05:17 CDT