check that table used in multi-update is unique added (BUG#5455)

mysql-test/r/multi_update.result

@@ -455,3 +455,10 @@ create table t3 (a int, primary key (a));
 delete t1,t3 from t1,t2 where t1.a=t2.a and t2.a=(select t3.a from t3 where t1.a=t3.a);
 ERROR 42S02: Unknown table 't3' in MULTI DELETE
 drop table t1, t2, t3;
+create table t1 (col1 int);
+create table t2 (col1 int);
+update t1,t2 set t1.col1 = (select max(col1) from t1) where t1.col1 = t2.col1;
+ERROR HY000: You can't specify target table 't1' for update in FROM clause
+delete t1 from t1,t2 where t1.col1 < (select max(col1) from t1) and t1.col1 = t2.col1;
+ERROR HY000: You can't specify target table 't1' for update in FROM clause
+drop table t1,t2;

mysql-test/t/multi_update.test

@@ -417,3 +417,14 @@ create table t3 (a int, primary key (a));
 -- error 1109
 delete t1,t3 from t1,t2 where t1.a=t2.a and t2.a=(select t3.a from t3 where t1.a=t3.a);
 drop table t1, t2, t3;
+
+#
+# multi* unique updating table check
+#
+create table t1 (col1 int); 
+create table t2 (col1 int);
+-- error 1093
+update t1,t2 set t1.col1 = (select max(col1) from t1) where t1.col1 = t2.col1;
+-- error 1093
+delete t1 from t1,t2 where t1.col1 < (select max(col1) from t1) and t1.col1 = t2.col1;
+drop table t1,t2;

sql/sql_lex.cc

@@ -1548,6 +1548,7 @@ bool st_select_lex::setup_ref_array(THD *thd, uint order_group_num)
     1 - found
     0 - OK (table did not found)
 */
+
 bool st_select_lex_unit::check_updateable(char *db, char *table)
 {
   for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
@@ -1559,7 +1560,7 @@ bool st_select_lex_unit::check_updateable(char *db, char *table)
 
 /*
   Find db.table which will be updated in this select and 
-  underlayed ones (except derived tables)
+  underlaying ones (except derived tables)
 
   SYNOPSIS
     st_select_lex::check_updateable()
@@ -1570,11 +1571,30 @@ bool st_select_lex_unit::check_updateable(char *db, char *table)
     1 - found
     0 - OK (table did not found)
 */
+
 bool st_select_lex::check_updateable(char *db, char *table)
 {
   if (find_real_table_in_list(get_table_list(), db, table))
     return 1;
 
+  return check_updateable_in_subqueries(db, table);
+}
+
+/*
+   Find db.table which will be updated in underlaying subqueries
+
+   SYNOPSIS
+    st_select_lex::check_updateable_in_subqueries()
+    db		- data base name
+    table	- real table name
+
+  RETURN
+    1 - found
+    0 - OK (table did not found)
+*/
+
+bool st_select_lex::check_updateable_in_subqueries(char *db, char *table)
+{
   for (SELECT_LEX_UNIT *un= first_inner_unit();
        un;
        un= un->next_unit())

sql/sql_lex.h

@@ -517,6 +517,7 @@ public:
   }
   bool setup_ref_array(THD *thd, uint order_group_num);
   bool check_updateable(char *db, char *table);
+  bool check_updateable_in_subqueries(char *db, char *table);
   void print(THD *thd, String *str);
   static void print_order(String *str, ORDER *order);
   void print_limit(THD *thd, String *str);

sql/sql_parse.cc

@@ -2796,24 +2796,19 @@ unsent_create_error:
 	 target_tbl;
 	 target_tbl= target_tbl->next)
     {
-      target_tbl->table= target_tbl->table_list->table;
-      /* 
+      TABLE_LIST *orig= target_tbl->table_list;
+      target_tbl->table= orig->table;
+      /*
 	 Multi-delete can't be constructed over-union => we always have
 	 single SELECT on top and have to check underlaying SELECTs of it
       */
-      for (SELECT_LEX_UNIT *un= lex->select_lex.first_inner_unit();
-	   un;
-	   un= un->next_unit())
+      if (lex->select_lex.check_updateable_in_subqueries(orig->db,
+                                                         orig->real_name))
       {
-	if (un->first_select()->linkage != DERIVED_TABLE_TYPE &&
-	    un->check_updateable(target_tbl->table_list->db,
-				 target_tbl->table_list->real_name))
-	{
-	  my_error(ER_UPDATE_TABLE_USED, MYF(0),
-		   target_tbl->table_list->real_name);
-	  res= -1;
-	  break;
-	}
+        my_error(ER_UPDATE_TABLE_USED, MYF(0),
+                 orig->real_name);
+        res= -1;
+        break;
       }
     }
 

sql/sql_update.cc

@@ -490,9 +490,8 @@ int mysql_multi_update(THD *thd,
       table->grant.want_privilege= (UPDATE_ACL & ~table->grant.privilege);
   }
 
-  if (thd->lex->derived_tables)
+  /* Assign table map values to check updatability of derived tables */
   {
-    // Assign table map values to check updatability of derived tables
     uint tablenr=0;
     for (TABLE_LIST *table_list= update_list;
 	 table_list;
@@ -501,11 +500,12 @@ int mysql_multi_update(THD *thd,
       table_list->table->map= (table_map) 1 << tablenr;
     }
   }
+
   if (setup_fields(thd, 0, update_list, *fields, 1, 0, 0))
     DBUG_RETURN(-1);
-  if (thd->lex->derived_tables)
+
+  /* Find tables used in items */
   {
-    // Find tables used in items
     List_iterator_fast<Item> it(*fields);
     Item *item;
     while ((item= it++))
@@ -527,7 +527,23 @@ int mysql_multi_update(THD *thd,
     if (table->timestamp_field &&
         table->timestamp_field->query_id == thd->query_id)
       table->timestamp_on_update_now= 0;
-    
+
+    /* if table will be updated then check that it is unique */
+    if (table->map & item_tables)
+    {
+      /*
+	 Multi-update can't be constructed over-union => we always have
+	 single SELECT on top and have to check underlaying SELECTs of it
+      */
+      if (select_lex->check_updateable_in_subqueries(tl->db,
+                                                     tl->real_name))
+      {
+        my_error(ER_UPDATE_TABLE_USED, MYF(0),
+                 tl->real_name);
+        DBUG_RETURN(-1);
+      }
+    }
+
     if (tl->derived)
       derived_tables|= table->map;
   }