Fix for BUG#25082: default database change on trigger

execution breaks replication.

When a stored routine is executed, we switch current
database to the database, in which the routine
has been created. When the stored routine finishes,
we switch back to the original database.

The problem was that if the original database does not
exist (anymore) after routine execution, we raised an error.

The fix is to report a warning, and switch to the NULL database.


mysql-test/r/sp.result:
  Updated result file.
mysql-test/t/sp.test:
  Added test case for BUG#25082.
sql/mysql_priv.h:
  1. Change mysql_change_db() prototype;
  2. Polishing.
sql/sp.cc:
  Polishing.
sql/sp_head.cc:
  Polishing.
sql/sql_db.cc:
  1. Polishing.
  2. Fix mysql_change_db().
sql/sql_parse.cc:
  Polishing.
sql/sql_show.cc:
  Polishing.

1 files changed, 15 insertions, 0 deletions

diff --git a/mysql-test/r/sp.result b/mysql-test/r/sp.result
index ddd2369d36d..6773facb641 100644
--- a/mysql-test/r/sp.result
+++ b/mysql-test/r/sp.result
@@ -5969,6 +5969,21 @@ SUM(f2)	bug25373(f1)
 21.300000071526	NULL
 DROP FUNCTION bug25373|
 DROP TABLE t3|
+DROP DATABASE IF EXISTS mysqltest1|
+DROP DATABASE IF EXISTS mysqltest2|
+CREATE DATABASE mysqltest1|
+CREATE DATABASE mysqltest2|
+CREATE PROCEDURE mysqltest1.p1()
+DROP DATABASE mysqltest2|
+use mysqltest2|
+CALL mysqltest1.p1()|
+Warnings:
+Note	1049	Unknown database 'mysqltest2'
+SELECT DATABASE()|
+DATABASE()
+NULL
+DROP DATABASE mysqltest1|
+use test|
 drop table t1,t2;
 CREATE TABLE t1 (a int auto_increment primary key) engine=MyISAM;
 CREATE TABLE t2 (a int auto_increment primary key, b int) engine=innodb;