Bug#18345346 Assertion failed: table_ref->view && table_ref->table == 0

An assert was misplaced in mysql_multi_delete_prepare(), which might
trigger for an attempted multi-table update on a view that was defined
over  multiple tables.

The assert has been refined and moved out of the error check.

Author: roylyseng

mysql-test/r/delete.result

@@ -559,3 +559,14 @@ Error	1451	Cannot delete or update a parent row: a foreign key constraint fails
 DEALLOCATE PREPARE stm;
 DROP TABLE t2, t1;
 DROP PROCEDURE p1;
+#
+# Bug#18345346 Assertion failed: table_ref->view && table_ref->table == 0
+#
+CREATE TABLE b(a INTEGER);
+CREATE VIEW y AS SELECT 1 FROM b, b AS e;
+CREATE VIEW x AS SELECT 1 FROM y;
+CREATE VIEW z AS SELECT 1 FROM x LIMIT 1;
+DELETE z FROM (SELECT 1) AS x, z;
+ERROR HY000: Can not delete from join view 'test.z'
+DROP VIEW z, x, y;
+DROP TABLE b;

mysql-test/t/delete.test

@@ -632,3 +632,18 @@ DEALLOCATE PREPARE stm;
 
 DROP TABLE t2, t1;
 DROP PROCEDURE p1;
+
+--echo #
+--echo # Bug#18345346 Assertion failed: table_ref->view && table_ref->table == 0
+--echo #
+
+CREATE TABLE b(a INTEGER);
+CREATE VIEW y AS SELECT 1 FROM b, b AS e;
+CREATE VIEW x AS SELECT 1 FROM y;
+CREATE VIEW z AS SELECT 1 FROM x LIMIT 1;
+
+--error ER_VIEW_DELETE_MERGE_VIEW
+DELETE z FROM (SELECT 1) AS x, z;
+
+DROP VIEW z, x, y;
+DROP TABLE b;

sql/sql_delete.cc

@@ -722,7 +722,6 @@ int mysql_multi_delete_prepare(THD *thd, uint *table_count)
     // DELETE does not allow deleting from multi-table views
     if (table_ref->multitable_view)
     {
-      DBUG_ASSERT(table_ref->view && table_ref->table == NULL);
       my_error(ER_VIEW_DELETE_MERGE_VIEW, MYF(0),
                table_ref->view_db.str, table_ref->view_name.str);
       DBUG_RETURN(true);
@@ -736,6 +735,9 @@ int mysql_multi_delete_prepare(THD *thd, uint *table_count)
       DBUG_RETURN(true);
     }
 
+    // A view must be merged, and thus cannot have a TABLE 
+    DBUG_ASSERT(!table_ref->view || table_ref->table == NULL);
+
     // Enable the following code if allowing LIMIT with multi-table DELETE
     DBUG_ASSERT(select->select_limit == 0);