Forgot to add; another option is to use a PL function with an exception handler. This may be a bit more elegant approach but not necessarily easier.
FYI Jerry Sievers <[EMAIL PROTECTED]> writes: > Benjamin Smith <[EMAIL PROTECTED]> writes: > > > I want to be able to determine in advance whether or not a record is > > "deleteable" before displaying the button to delete the record. If it's not > > deleteable, it should say so before the user hits the button. > > > > But, the only way that I've been able to find out if the customer record is > > deletable is to begin a transaction, try to delete it, check to see if it > > worked, and then rollback the session. > > > > This causes my error logger to log errors everytime somebody looks at a > > customer record, and (I'm sure) is not very efficient. > > > > Is there a way to ask the database: "Are there any FK constraints that > > would > > prevent this record from being deleted?" > > Short of your own fancy function that walks the FK tree, no. (BTW, > this could be simple actually if the FK linkage is shallow.) > > Add a statement to prevent the nuisance error message to the trans. > > begin; > set log_min_messages to log; > do trial delete; > rollback; > > HTH > > > -- > ------------------------------------------------------------------------------- > Jerry Sievers 305 854-3001 (home) WWW ECommerce Consultant > 305 321-1144 (mobile http://www.JerrySievers.com/ > > ---------------------------(end of broadcast)--------------------------- > TIP 9: In versions below 8.0, the planner will ignore your desire to > choose an index scan if your joining column's datatypes do not > match > -- ------------------------------------------------------------------------------- Jerry Sievers 305 854-3001 (home) WWW ECommerce Consultant 305 321-1144 (mobile http://www.JerrySievers.com/ ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
