Syntax:
CONVERT(expr,type), CONVERT(expr USING transcoding_name)

The CONVERT() and CAST() functions take an expression of any type and
produce a result value of a specified type.

CAST() and CONVERT(... USING ...) are standard SQL syntax. The
non-USING form of CONVERT() is ODBC syntax.

CONVERT() with USING converts data between different character sets. In
MySQL, transcoding names are the same as the corresponding character
set names. For example, this statement converts the string 'abc' in the
default character set to the corresponding string in the utf8 character
set:

SELECT CONVERT('abc' USING utf8);

The type for the result can be one of the following values:

o BINARY[(N)]

o CHAR[(N)]

o DATE

o DATETIME

o DECIMAL[(M[,D])]

o SIGNED [INTEGER]

o TIME

o UNSIGNED [INTEGER]

BINARY produces a string with the BINARY data type. See
http://dev.mysql.com/doc/refman/5.5/en/binary-varbinary.html for a
description of how this affects comparisons. If the optional length N
is given, BINARY(N) causes the cast to use no more than N bytes of the
argument. Values shorter than N bytes are padded with 0x00 bytes to a
length of N.

CHAR(N) causes the cast to use no more than N characters of the
argument.

URL: http://dev.mysql.com/doc/refman/5.5/en/cast-functions.html

