bug 617963, Better cascading of collections table.

migrations/104-collections-cascade.sql

@@ -0,0 +1,10 @@
+SET FOREIGN_KEY_CHECKS=0;
+
+ALTER TABLE `collections` DROP FOREIGN KEY `collections_ibfk_7`;
+
+ALTER TABLE `collections` ADD CONSTRAINT `collections_ibfk_7`
+    FOREIGN KEY `collections_ibfk_7` (`author_id`)
+    REFERENCES `users` (`id`)
+    ON DELETE CASCADE;
+
+SET FOREIGN_KEY_CHECKS=1;