+(defsql sql-coalesce (:symbol "coalesce") (&rest rest)
+ (make-instance 'sql-function-exp
+ :name 'coalesce :args rest))
+
+(defsql sql-nvl (:symbol "nvl") (&rest rest)
+ (if (= (length rest) 2)
+ (make-instance 'sql-function-exp
+ :name 'coalesce :args rest)
+ (error 'sql-user-error :message "NVL accepts exactly 2 arguments.")))
+
+(defsql sql-userenv (:symbol "userenv") (&rest rest)
+ (make-instance 'sql-function-exp
+ :name 'userenv :args rest))