Bug #31006 problem of concat() and concat_ws() with german "Umlaute" and int fields

Description:
The query:
"select pk, name, concat(pk,name) from test_table;"
results in
+------+------+-----------------+
| pk   | name | concat(pk,name) |
+------+------+-----------------+
|    1 | ä    | 1À             |
+------+------+-----------------+

expected was "1ä" for the concatenation.
However
"select pk, name, concat(cast(pk as char),name) from test_table;"
results in
+------+------+-------------------------------+
| pk   | name | concat(cast(pk as char),name) |
+------+------+-------------------------------+
|    1 | ä    | 1ä                            |
+------+------+-------------------------------+

which is the correct (expected) result.

The query
"select concat(1,'ä');"
also works correct.

Table definition:

CREATE TABLE `test_table` (
  `pk` int(11) default NULL,
  `name` varchar(100) default NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 |

Characterset settings:
| character_set_client     | latin1                     |
| character_set_connection | latin1                     |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | latin1                     |
| character_set_server     | latin1                     |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |

How to repeat:
see above

Suggested fix:
-

Thank you for the bug report.

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mysql> CREATE TABLE `test_table` (
    ->   `pk` int(11) default NULL,
    ->   `name` varchar(100) default NULL
    -> ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.03 sec)

mysql> insert into test_table values (1,'ä');
Query OK, 1 row affected (0.00 sec)

mysql> insert into test_table values (1,'a');
Query OK, 1 row affected (0.00 sec)

mysql> select pk, name, concat(pk,name) from test_table;
+------+------+-----------------+
| pk   | name | concat(pk,name) |
+------+------+-----------------+
|    1 | ä    | 1ä             | 
|    1 | a    | 1a              | 
+------+------+-----------------+
2 rows in set (0.00 sec)

mysql>

This problem is a duplicate of http://bugs.mysql.com/bug.php?id=8204

As a workaround you need to use explicit conversion from number
to char():

mysql> select pk, name, concat(pk,name), concat((cast(pk as char)),name) from test_table;
+------+------+-----------------+---------------------------------+
| pk   | name | concat(pk,name) | concat((cast(pk as char)),name) |
+------+------+-----------------+---------------------------------+
|    1 | ä    | 1ä             | 1ä                              |
|    1 | a    | 1a              | 1a                              |
+------+------+-----------------+---------------------------------+
2 rows in set (0.00 sec)

Marking this bug as duplicate to 8204.