CHAR(N,... [USING charset_name])
CHAR() interprets each argument N as an integer.
NULL values are skipped.
By default, CHAR() returns a binary string.
mysql>
mysql> SELECT CHAR(7,2,3,4,5);
+-----------------+
| CHAR(7,2,3,4,5) |
+-----------------+
| |
+-----------------+
1 row in set (0.00 sec)