anchor.diff:  (in-package :postgres-json)
   
  -;; (defclass postgres-json-persist-model () ())
  -
  -;; (defclass cat (postgres-json-persist-model) ())
  -
  -;; (defgeneric insert$ (id json)
  -;;   (:documentation "Insert JSON into a Postgres relation using primary
  -;; key ID."))
  -
  -;; (defmethod insert$ (()))
  +;;;; Query management
   
   (defparameter *query-functions* (make-hash-table :test #'equal))
   
  
positive.code:                                                       'valid-from
                                                        ',*jdoc*
                                                        :from ,table
                                                        :where (:= ',*id* '$1))
                                               :returning ',*id*)))))
  
  (defun make-update$ (model table)
    (setf (lookup-query model 'update$)
  
negative.code: 
  (defun make-insert$ (model table)
    (setf (lookup-query model 'insert$)
          (prepare (sql-compile `(:insert-into ,table :set ',*id* '$1 ',*jdoc* '$2
                                               :returning ',*id*))
              :single!)))
  
  (defun make-insert-old$ (model table old-table)
    (setf (lookup-query model 'insert-old$)
  