make multi updates statistics visible in SHOW STATUS as Com_update_multi

sql/mysqld.cc

@@ -4048,6 +4048,7 @@ struct show_var_st status_vars[]= {
   {"Com_truncate",	       (char*) (com_stat+(uint) SQLCOM_TRUNCATE),SHOW_LONG},
   {"Com_unlock_tables",	       (char*) (com_stat+(uint) SQLCOM_UNLOCK_TABLES),SHOW_LONG},
   {"Com_update",	       (char*) (com_stat+(uint) SQLCOM_UPDATE),SHOW_LONG},
+  {"Com_update_multi",	       (char*) (com_stat+(uint) SQLCOM_UPDATE_MULTI),SHOW_LONG},
   {"Connections",              (char*) &thread_id,              SHOW_LONG_CONST},
   {"Created_tmp_disk_tables",  (char*) &created_tmp_disk_tables,SHOW_LONG},
   {"Created_tmp_tables",       (char*) &created_tmp_tables,     SHOW_LONG},

sql/sql_parse.cc

@@ -1894,8 +1894,6 @@ mysql_execute_command(THD *thd)
       send_error(thd,ER_WRONG_VALUE_COUNT);
       DBUG_VOID_RETURN;
     }
-    if (select_lex->table_list.elements == 1)
-    {
     res= mysql_update(thd,tables,
                       select_lex->item_list,
                       lex->value_list,
@@ -1903,15 +1901,23 @@ mysql_execute_command(THD *thd)
                       (ORDER *) select_lex->order_list.first,
                       select_lex->select_limit,
                       lex->duplicates);
+    break;
+  case SQLCOM_UPDATE_MULTI:
+    if (check_access(thd,UPDATE_ACL,tables->db,&tables->grant.privilege))
+      goto error;
+    if (grant_option && check_grant(thd,UPDATE_ACL,tables))
+      goto error;
+    if (select_lex->item_list.elements != lex->value_list.elements)
+    {
+      send_error(thd,ER_WRONG_VALUE_COUNT);
+      DBUG_VOID_RETURN;
     }
-    else
     {
       multi_update  *result;
       uint table_count;
       TABLE_LIST *auxi;
       const char *msg=0;
 
-      lex->sql_command=SQLCOM_UPDATE_MULTI;
       for (auxi= (TABLE_LIST*) tables, table_count=0 ; auxi ; auxi=auxi->next)
 	table_count++;
 

sql/sql_yacc.yy

@@ -3061,6 +3061,8 @@ update:
 	SET update_list where_clause opt_order_clause delete_limit_clause
 	{
 	  Select->set_lock_for_tables($3);
+          if (lex->select_lex->table_list.elements > 1)
+            lex->sql_command=SQLCOM_UPDATE_MULTI;
 	}
 	;