Fix for bug #13525 "Rename table does not keep info of triggers".

Let us transfer triggers associated with table when we rename it (but only if
we are not changing database to which table belongs, in the latter case we will
emit error).


mysql-test/r/trigger.result:
  Added test for bug #13525 "Rename table does not keep info of triggers".
mysql-test/t/trigger.test:
  Added test for bug #13525 "Rename table does not keep info of triggers".
sql/sql_rename.cc:
  rename_tables():
    Now after renaming table's .FRM file and updating handler data we call
    Table_triggers_list::change_table_name() which is reponsible for
    updating .TRG and .TRN files.
sql/sql_table.cc:
  mysql_alter_table():
    Now in case when ALTER should rename table we call
    Table_triggers_list::change_table_name() which is responsible
    for updating .TRG and .TRN files after renaming table.
sql/sql_trigger.cc:
  Added Table_triggers_list::change_table_name() method and
  change_table_name_in_triggers()/trignames() methods responsible for updating
  .TRG and .TRN files for table during its renaming.
  
  Two small cleanups - removed versioning for .TRG files (since it was not working
  before anyway) and emphasized that type of lock specified in tables list is
  unimportant for DROP TABLE (since this statement uses name-locking).
sql/sql_trigger.h:
  Table_triggers_list:
    Added on_table_names_list member to store pointers and lenghts of
    "ON table_name" parts in triggers' definitions to be able easily
    change them during RENAME TABLE.
    Added change_table_name() method and change_table_name_in_trignames/triggers()
    helper methods responsible for updating .TRG and .TRN files.
sql/sql_yacc.yy:
  trigger_tail:
    To be able properly update triggers' definitions with new table names
    when renaming tables we need to know where in CREATE TRIGGER statement
    "ON db_name.table_name" part resides.
    Small cleanup - let us emphasize that for CREATE TRIGGER statement 
    lock type which is specified in table list is unimportant since
    name-locking is used.

mysql-test/t/trigger.test

@@ -3,7 +3,7 @@
 #
 
 --disable_warnings
-drop table if exists t1, t2, t3;
+drop table if exists t1, t2, t3, t4;
 drop view if exists v1;
 drop database if exists mysqltest;
 drop function if exists f1;
@@ -961,3 +961,88 @@ create trigger test.t1_bi before insert on t1 for each row set @a:=0;
 --error ER_NO_DB_ERROR
 drop trigger t1_bi;
 connection default;
+
+#
+# Test for bug #13525 "Rename table does not keep info of triggers"
+#
+create table t1 (id int);
+create trigger t1_bi before insert on t1 for each row set @a:=new.id;
+insert into t1 values (101);
+select @a;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test';
+rename table t1 to t2;
+# Trigger should work after rename
+insert into t2 values (102);
+select @a;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test';
+# Let us check that the same works for simple ALTER TABLE ... RENAME
+alter table t2 rename to t3;
+insert into t3 values (103);
+select @a;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test';
+# And for more complex ALTER TABLE
+alter table t3 rename to t4, add column val int default 0;
+insert into t4 values (104, 1);
+select @a;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test';
+# .TRN file should be updated with new table name
+drop trigger t1_bi;
+drop table t4;
+# Rename between different databases if triggers exist should fail
+create database mysqltest;
+use mysqltest;
+create table t1 (id int);
+create trigger t1_bi before insert on t1 for each row set @a:=new.id;
+insert into t1 values (101);
+select @a;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test' or event_object_schema = 'mysqltest';
+--error ER_TRG_IN_WRONG_SCHEMA
+rename table t1 to test.t2;
+insert into t1 values (102);
+select @a;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test' or event_object_schema = 'mysqltest';
+# There should be no fantom .TRN files 
+--error ER_TRG_DOES_NOT_EXIST
+drop trigger test.t1_bi;
+drop trigger t1_bi;
+drop table t1;
+drop database mysqltest;
+use test;
+# And now let us check that the properly handle rename if there is some
+# error during it (that we rollback such renames completely).
+create table t1 (id int);
+create trigger t1_bi before insert on t1 for each row set @a:=new.id;
+create trigger t1_ai after insert on t1 for each row set @b:=new.id;
+insert into t1 values (101);
+select @a, @b;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test';
+# Trick which makes update of second .TRN file impossible
+system echo dummy >var/master-data/test/t1_ai.TRN~;
+system chmod 000 var/master-data/test/t1_ai.TRN~;
+--error 1
+rename table t1 to t2;
+# 't1' should be still there and triggers should work correctly
+insert into t1 values (102);
+select @a, @b;
+select trigger_schema, trigger_name, event_object_schema,
+       event_object_table, action_statement from information_schema.triggers
+       where event_object_schema = 'test';
+system chmod 600 var/master-data/test/t1_ai.TRN;
+# Let us check that updates to .TRN files were rolled back too
+drop trigger t1_bi;
+drop trigger t1_ai;
+drop table t1;