Fix for bug#12127 triggers do not show in info_schema before they are used if...

Fix for bug#12127 triggers do not show in info_schema before they are used if set to the database(2nd version)
  use db name of table which trigger belongs to
  instead of thd->db name during trigger body parsing

mysql-test/r/information_schema.result

@@ -940,3 +940,12 @@ f5	19	NULL
 f6	1	NULL
 f7	64	NULL
 drop table t1;
+create table t1 (f1 integer);
+create trigger tr1 after insert on t1 for each row set @test_var=42;
+use information_schema;
+select trigger_schema, trigger_name from triggers where
+trigger_name='tr1';
+trigger_schema	trigger_name
+test	tr1
+use test;
+drop table t1;

mysql-test/t/information_schema.test

@@ -622,3 +622,14 @@ select column_name, NUMERIC_PRECISION, NUMERIC_SCALE
 from information_schema.columns
 where table_name='t1';
 drop table t1;
+
+#
+# Bug #12127 triggers do not show in info_schema before they are used if set to the database
+#
+create table t1 (f1 integer);
+create trigger tr1 after insert on t1 for each row set @test_var=42;
+use information_schema;
+select trigger_schema, trigger_name from triggers where
+trigger_name='tr1';
+use test;
+drop table t1;

sql/sql_trigger.cc

@@ -520,6 +520,7 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
   char path_buff[FN_REFLEN];
   LEX_STRING path;
   File_parser *parser;
+  LEX_STRING save_db;
 
   DBUG_ENTER("Table_triggers_list::check_n_load");
 
@@ -581,6 +582,10 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
 
       thd->lex= &lex;
 
+      save_db.str= thd->db;
+      save_db.length= thd->db_length;
+      thd->db_length= strlen(db);
+      thd->db= (char *) db;
       while ((trg_create_str= it++))
       {
         lex_start(thd, (uchar*)trg_create_str->str, trg_create_str->length);
@@ -623,6 +628,8 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
 
         lex_end(&lex);
       }
+      thd->db= save_db.str;
+      thd->db_length= save_db.length;
       thd->lex= old_lex;
 
       DBUG_RETURN(0);
@@ -631,6 +638,8 @@ err_with_lex_cleanup:
       // QQ: anything else ?
       lex_end(&lex);
       thd->lex= old_lex;
+      thd->db= save_db.str;
+      thd->db_length= save_db.length;
       DBUG_RETURN(1);
     }