mysql> CREATE TABLE t (
 -> a BINARY(1)
 -> )ENGINE=InnoDB CHARSET=GBK;
Query OK, 0 rows affected (0.02 sec)

mysql> SET NAMES GBK;
Query OK, 0 rows affected (0.00 sec)

MySQL> INSERT INTO t SELECT '我';
Query OK, 1 row affected, 1 warning (0.01 sec)
Records: 1 Duplicates: 0 Warnings: 1

mysql> SHOW WARNINGS\G;
*************************** 1. row ***************************
 Level: Warning
 Code: 1265
Message: Data truncated for column 'a' at row 1
1 row in set (0.00 sec)

mysql> SELECT a,HEX(a) FROM t\G;
*************************** 1. row ***************************
 a:
HEX(a): CE

mysql> CREATE TABLE t (
 -> a CHAR(1)
 -> )ENGINE=InnoDB CHARSET=GBK;
Query OK, 0 rows affected (0.02 sec)

mysql> INSERT INTO t SELECT '我';
Query OK, 1 row affected, 1 warning (0.01 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> SELECT a,HEX(a) FROM t\G;
*************************** 1. row ***************************
 a: 我
HEX(a): CED2
1 row in set (0.00 sec)

mysql> SELECT
 -> HEX('a'),
 -> HEX('a '),
 -> 'a'='a '\G; 
*************************** 1. row ***************************
HEX('a'): 61
HEX('a '): 612020
'a'='a ': 1
1 row in set (0.00 sec)

mysql> SELECT
 -> HEX(BINARY('a')),
 -> HEX(BINARY('a ')),
 -> BINARY('a')= BINARY('a ')\G; 
*************************** 1. row ***************************
  HEX(BINARY('a')): 61
 HEX(BINARY('a ')): 612020
BINARY('a')= BINARY('a '): 0
1 row in set (0.00 sec)

mysql> CREATE TABLE t ( a BINARY(3));
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO t SELECT 'a';
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> SELECT a,HEX(a) FROM t\G;
*************************** 1. row ***************************
 a: a
HEX(a): 610000
1 row in set (0.00 sec)