String comparisons are not case sensitive unless one of the operands is a binary string : LIKE « String Functions « MySQL Tutorial

mysql>
mysql> SELECT 'abc' LIKE 'ABC';
+------------------+
| 'abc' LIKE 'ABC' |
+------------------+
|                1 |
+------------------+
1 row in set (0.00 sec)

mysql>
mysql> SELECT 'abc' LIKE BINARY 'ABC';
+-------------------------+
| 'abc' LIKE BINARY 'ABC' |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set (0.00 sec)

mysql>

23.21.LIKE
	23.21.1.	expr LIKE pat [ESCAPE 'escape_char']
	23.21.2.	To test for literal instances of a wildcard character, precede it by the escape character.
	23.21.3.	To specify a different escape character, use the ESCAPE clause:
	23.21.4.	String comparisons are not case sensitive unless one of the operands is a binary string
	23.21.5.	In MySQL, LIKE is allowed on numeric expressions.