insert only if conditions are met?

Is there a way to insert a record only if a certain<br /> condition is met?<br /><br /> Something like:<br /> insert
intoemployee values('lastname','firstname',8) where<br /> (condition here.. select sum(ofsomething) from xx where
sum(ofsomething)>0)<br /><br /> Is this possible at all with just plain SQL?<br />