Subselects in CHECK clause ...

[James Robinson <jlrobins(at)socialserve(dot)com>]

I see that subselects are not directly supported in check clauses,  
but one can work around that by writing a stored function which  
returns boolean and performs the subselect. Are there any known  
gotchas with doing this?

The CREATE TABLE docs regarding CHECK clauses states:

	"Currently, CHECK expressions cannot contain subqueries nor refer to  
variables other than columns of the current row."

Is this due to someone not yet writing the necessary code to remove  
the subquery clause, or is there a more fundamental reason?

----
James Robinson
Socialserve.com