MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6

10.10.8 The Binary Character Set

The binary character set is the character set for binary strings, which are sequences of bytes. The binary character set has one collation, also named binary. Comparison and sorting are based on numeric byte values, rather than on numeric character code values (which for multibyte characters differ from numeric byte values). For information about the differences between the binary collation of the binary character set and the _bin collations of nonbinary character sets, see Section 10.8.5, “The binary Collation Compared to _bin Collations”.

For the binary character set, the concepts of lettercase and accent equivalence do not apply:

To perform lettercase conversion of a binary string, first convert it to a nonbinary string using a character set appropriate for the data stored in the string:

mysql> SET @str = BINARY 'New York';
mysql> SELECT LOWER(@str), LOWER(CONVERT(@str USING utf8mb4));
+-------------+------------------------------------+
| LOWER(@str) | LOWER(CONVERT(@str USING utf8mb4)) |
+-------------+------------------------------------+
| New York    | new york                           |
+-------------+------------------------------------+

To convert a string expression to a binary string, these constructs are equivalent:

BINARY expr
CAST(expr AS BINARY)
CONVERT(expr USING BINARY)

If a value is a character string literal, the _binary introducer may be used to designate it as a binary string. For example:

_binary 'a'

The _binary introducer is permitted for hexadecimal literals and bit-value literals as well, but unnecessary; such literals are binary strings by default.

For more information about introducers, see Section 10.3.8, “Character Set Introducers”.