[postmodern-devel] IF-EXISTS operator for DROP-* ops

[Daniel White]

I'm wanting to use the IF EXISTS modifier for the various DROP
operations, and it seems like the semantics of CASCADE works best for
this case.

The following is a proof of concept implementation.  If there aren't
any issues or complaints I'll write a patch that covers the rest of
the DROP operations.

(defvar *expand-if-exists* nil)

(defun expand-if-exists ()
  (when *expand-if-exists*
    `("IF EXISTS ")))

(def-sql-op :if-exists (op)
  (let ((*expand-if-exists* t))
    (sql-expand op)))

(def-sql-op :drop-sequence (name)
  `("DROP SEQUENCE " ,@(expand-if-exists) ,@(sql-expand name)))

(sql (:if-exists (:drop-sequence 'sequence)))

Cheers,
-- 
Daniel White