feat: 2 new triggers to purchase smthing.

PostgreSQL/src/create.sql

@@ -407,7 +407,7 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
-CREATE TRIGGER note_veryfier
+CREATE TRIGGER trigger_note_veryfier
 BEFORE INSERT OR UPDATE ON noter
 FOR EACH ROW
 EXECUTE FUNCTION note_veryfier();
@@ -447,10 +447,52 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
-CREATE TRIGGER delete_cascade_piece
+CREATE TRIGGER trigger_delete_cascade_piece
 AFTER DELETE ON pieces
 FOR EACH ROW
 EXECUTE FUNCTION delete_cascade_piece();
 
+-- Not to buy more than it is possible : quantite_acheter < quantite_contenir.
+
+CREATE OR REPLACE FUNCTION verify_availability_purchase()
+RETURNS TRIGGER AS $$
+BEGIN
+    IF (SELECT quantite_contenir 
+        FROM contenir 
+        WHERE id_boite 
+            IN (SELECT id_boite FROM contenir WHERE id_piece = NEW.id_piece) 
+        AND id_piece = NEW.id_piece) < NEW.quantite_acheter THEN
+        RAISE EXCEPTION 'quantite_acheter < quantite_contenir';
+    END IF;
+
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER trigger_verify_purchase
+BEFORE INSERT ON acheter
+FOR EACH ROW
+EXECUTE FUNCTION verify_availability_purchase();
+
+-- When a purchase is done, remove the pieces from contenir.
+
+CREATE OR REPLACE FUNCTION after_set_purchase()
+RETURNS TRIGGER AS $$
+BEGIN
+    UPDATE contenir
+    SET quantite_contenir = quantite_contenir - NEW.quantite_acheter
+    WHERE id_piece = NEW.id_piece
+    AND id_boite 
+        IN (SELECT id_boite FROM contenir WHERE id_piece = NEW.id_piece);
+
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER trigger_set_purchase
+AFTER INSERT ON acheter
+FOR EACH ROW
+EXECUTE FUNCTION after_set_purchase();
+
 -- ============================================================================