diff --git a/database/task-containers.sql b/database/task-containers.sql
index edb44ad..7403d2c 100644
--- a/database/task-containers.sql
+++ b/database/task-containers.sql
@@ -139,3 +139,32 @@ REVOKE EXECUTE
 CREATE TRIGGER tasks_item_au
 	AFTER UPDATE OF item_id ON tasks
 	FOR EACH ROW EXECUTE PROCEDURE tasks_item_au( );
+
+
+/*
+ * After an update on some task's logical container, set the task's parent ID.
+ */
+DROP FUNCTION IF EXISTS tasks_item_au( ) CASCADE;
+CREATE FUNCTION tasks_ltc_au( )
+		RETURNS TRIGGER
+		LANGUAGE PLPGSQL
+		SECURITY DEFINER
+	AS $tasks_ltc_au$
+BEGIN
+	UPDATE tasks
+		SET task_id_parent = (
+			SELECT task_id
+				FROM logical_task_containers
+				WHERE ltc_id = NEW.ltc_id )
+		WHERE task_id = NEW.task_id;
+	RETURN NEW;
+END;
+$tasks_ltc_au$;
+
+REVOKE EXECUTE
+	ON FUNCTION tasks_ltc_au( )
+	FROM PUBLIC;
+
+CREATE TRIGGER tasks_ltc_au
+	AFTER UPDATE OF ltc_id ON tasks
+	FOR EACH ROW EXECUTE PROCEDURE tasks_ltc_au( );
diff --git a/database/upgrade/from-bca6b99068cbf1dd4148d6bd5cb60e926162cfe1.sql b/database/upgrade/from-bca6b99068cbf1dd4148d6bd5cb60e926162cfe1.sql
new file mode 100644
index 0000000..b44ea05
--- /dev/null
+++ b/database/upgrade/from-bca6b99068cbf1dd4148d6bd5cb60e926162cfe1.sql
@@ -0,0 +1,37 @@
+--
+-- Upgrade the database from commit ID bca6b99068cbf1dd4148d6bd5cb60e926162cfe1
+--
+-- Run this from the top-level directory
+--
+
+
+\i database/config.sql
+\c :db_name
+
+BEGIN;
+
+	DROP FUNCTION IF EXISTS tasks_item_au( ) CASCADE;
+	CREATE FUNCTION tasks_ltc_au( )
+			RETURNS TRIGGER
+			LANGUAGE PLPGSQL
+			SECURITY DEFINER
+		AS $tasks_ltc_au$
+	BEGIN
+		UPDATE tasks
+			SET task_id_parent = (
+				SELECT task_id
+					FROM logical_task_containers
+					WHERE ltc_id = NEW.ltc_id )
+			WHERE task_id = NEW.task_id;
+		RETURN NEW;
+	END;
+	$tasks_ltc_au$;
+
+	REVOKE EXECUTE
+		ON FUNCTION tasks_ltc_au( )
+		FROM PUBLIC;
+
+	CREATE TRIGGER tasks_ltc_au
+		AFTER UPDATE OF ltc_id ON tasks
+		FOR EACH ROW EXECUTE PROCEDURE tasks_ltc_au( );
+COMMIT;