add support for left joins

septeql.lisp

@@ -156,6 +156,12 @@ interpolated into a SQL statement as a string literal"
       (setf r (make-instance 'sql :from r)))
     (make-instance 'sql :from `(join ,(sv l 'from) ,(sv r 'from) ,expr))))
 
+(define-translator left-join (rel1 rel2 expr)
+  (let* ((j (parse-relation `(join ,rel1 ,rel2 ,expr)))
+	 (from (sv j 'from)))
+    (setf (sv j 'from) `(left-join ,@(cdr from)))
+    j))
+
 (define-translator group (aggregates dividers relation)
   (let ((l (parse-relation relation)))
     (when (any-slot-bound-p l '(start end group-by attributes order-by))
@@ -223,6 +229,11 @@ interpolated into a SQL statement as a string literal"
 		 (from-clause-as-string  (second from))
 		 (from-clause-as-string  (third from))
 		 (translate-scalar (fourth from))))
+	((eql (car from) 'left-join)	 
+	 (format nil "(~A LEFT JOIN ~A ON ~A)"
+		 (from-clause-as-string  (second from))
+		 (from-clause-as-string  (third from))
+		 (translate-scalar (fourth from))))
 	(t (error "buggered if I know"))))
 
 (defun as-string (sql)

tests.lisp

@@ -135,4 +135,8 @@ SIMPLE-ERROR
 ;; sent
 (to-sql '(select relation (and (= value 1) (< another 10) (or true false))))
 ;; received
-"SELECT * FROM RELATION WHERE (((VALUE = 1) AND (ANOTHER < 10)) AND (TRUE OR FALSE)) "
+"SELECT * FROM RELATION WHERE (((VALUE = 1) AND (ANOTHER < 10)) AND (TRUE OR FALSE)) "
+;; sent
+(7ql:to-sql '(left-join a b (= a.id b.id)))
+;; received
+"SELECT * FROM (A LEFT JOIN B ON (A.ID = B.ID)) "