Merge mysql.com:/Users/davi/mysql/bugs/23771-5.1

into  mysql.com:/Users/davi/mysql/mysql-5.1-runtime

mysql-test/r/trigger.result

@@ -2016,4 +2016,42 @@ i	j
 10	10
 unlock tables;
 drop table t1;
+drop table if exists t1, t2;
+drop trigger if exists trg1;
+drop trigger if exists trg2;
+create table t1 (a int);
+create table t2 (b int);
+create trigger trg1 after update on t1 for each row set @a= @a+1;
+create trigger trg2 after update on t2 for each row set @b= @b+1;
+insert into t1 values (1), (2), (3);
+insert into t2 values (1), (2), (3);
+set @a= 0;
+set @b= 0;
+update t1, t2 set t1.a= t1.a, t2.b= t2.b;
+select @a, @b;
+@a	@b
+3	3
+update t1, t2 set t1.a= t2.b, t2.b= t1.a;
+select @a, @b;
+@a	@b
+6	6
+update t1 set a= a;
+select @a, @b;
+@a	@b
+9	6
+update t2 set b= b;
+select @a, @b;
+@a	@b
+9	9
+update t1 set a= 1;
+select @a, @b;
+@a	@b
+12	9
+update t2 set b= 1;
+select @a, @b;
+@a	@b
+12	12
+drop trigger trg1;
+drop trigger trg2;
+drop table t1, t2;
 End of 5.1 tests.

mysql-test/t/trigger.test

@@ -2304,4 +2304,37 @@ unlock tables;
 
 drop table t1;
 
+#
+# Bug#23771 AFTER UPDATE trigger not invoked when there are no changes of the data
+#
+
+--disable_warnings
+drop table if exists t1, t2;
+drop trigger if exists trg1;
+drop trigger if exists trg2;
+--enable_warnings
+create table t1 (a int);
+create table t2 (b int);
+create trigger trg1 after update on t1 for each row set @a= @a+1;
+create trigger trg2 after update on t2 for each row set @b= @b+1;
+insert into t1 values (1), (2), (3);
+insert into t2 values (1), (2), (3);
+set @a= 0;
+set @b= 0;
+update t1, t2 set t1.a= t1.a, t2.b= t2.b;
+select @a, @b;
+update t1, t2 set t1.a= t2.b, t2.b= t1.a;
+select @a, @b;
+update t1 set a= a;
+select @a, @b;
+update t2 set b= b;
+select @a, @b;
+update t1 set a= 1;
+select @a, @b;
+update t2 set b= 1;
+select @a, @b;
+drop trigger trg1;
+drop trigger trg2;
+drop table t1, t2;
+
 --echo End of 5.1 tests.

sql/sql_update.cc

@@ -643,14 +643,6 @@ int mysql_update(THD *thd,
             updated++;
           else
             error= 0;
-
-          if (table->triggers &&
-              table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
-                                                TRG_ACTION_AFTER, TRUE))
-          {
-            error= 1;
-            break;
-          }
 	}
  	else if (!ignore ||
                  table->file->is_fatal_error(error, HA_CHECK_DUP_KEY))
@@ -669,6 +661,14 @@ int mysql_update(THD *thd,
 	}
       }
 
+      if (table->triggers &&
+          table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
+                                            TRG_ACTION_AFTER, TRUE))
+      {
+        error= 1;
+        break;
+      }
+
       if (!--limit && using_limit)
       {
         /*
@@ -1644,13 +1644,13 @@ bool multi_update::send_data(List<Item> &not_used_values)
             trans_safe= 0;
             thd->transaction.stmt.modified_non_trans_table= TRUE;
           }
+        }
+      }
       if (table->triggers &&
           table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                             TRG_ACTION_AFTER, TRUE))
         DBUG_RETURN(1);
     }
-      }
-    }
     else
     {
       int error;
@@ -1881,13 +1881,13 @@ int multi_update::do_updates()
           updated++;
         else
           local_error= 0;
+      }
 
       if (table->triggers &&
           table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
                                             TRG_ACTION_AFTER, TRUE))
         goto err2;
     }
-    }
 
     if (updated != org_updated)
     {