Bug #11751148 : show events shows events in other schema

Issue:
------
Due to prefix match, database like 'k' was matching with 'ka' and events of 'ka' we getting displayed for 'show event' of 'k'.

Resolution:
-----------
Scan for listing of events in a schema is made to be done on exact match of database (schema) name instead of just prefix.

mysql-test/r/events_bugs.result

@@ -747,6 +747,15 @@ event_name	originator
 ev1	4294967295
 DROP EVENT ev1;
 SET GLOBAL server_id = @old_server_id;
+CREATE DATABASE event_test1;
+USE event_test1;
+CREATE EVENT ev1 ON SCHEDULE EVERY 1 DAY DO SELECT 1;
+CREATE DATABASE event_test2;
+USE event_test2;
+SHOW EVENTS;
+Db	Name	Definer	Time zone	Type	Execute at	Interval value	Interval field	Starts	Ends	Status	Originator	character_set_client	collation_connection	Database Collation
+DROP DATABASE event_test1;
+DROP DATABASE event_test2;
 DROP DATABASE events_test;
 SET GLOBAL event_scheduler= 'ON';
 SET @@global.concurrent_insert= @concurrent_insert;

mysql-test/t/events_bugs.test

@@ -1221,6 +1221,21 @@ SELECT event_name, originator FROM INFORMATION_SCHEMA.EVENTS;
 DROP EVENT ev1;
 SET GLOBAL server_id = @old_server_id;
 
+#
+# Bug#11751148: show events shows events in other schema
+#
+
+CREATE DATABASE event_test1;
+USE event_test1;
+CREATE EVENT ev1 ON SCHEDULE EVERY 1 DAY DO SELECT 1;
+CREATE DATABASE event_test2;
+USE event_test2;
+# Following show events should not show ev1
+SHOW EVENTS;
+DROP DATABASE event_test1;
+DROP DATABASE event_test2;
+
+
 ###########################################################################
 #
 # End of tests

sql/event_db_repository.cc

@@ -424,7 +424,7 @@ Event_db_repository::index_read_for_db_for_i_s(THD *thd, TABLE *schema_table,
   key_copy(key_buf, event_table->record[0], key_info, key_len);
   if (!(ret= event_table->file->index_read_map(event_table->record[0], key_buf,
                                                (key_part_map)1,
-                                               HA_READ_PREFIX)))
+                                               HA_READ_KEY_EXACT)))
   {
     DBUG_PRINT("info",("Found rows. Let's retrieve them. ret=%d", ret));
     do