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.

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/5.6/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.

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

CONVERT() with USING is used to convert 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);

URL: http://dev.mysql.com/doc/refman/5.6/en/cast-functions.html

