Syntax

BINARY(M)

Description

The BINARY type is similar to the CHAR type, but stores binary byte strings rather than non-binary character strings. M represents the column length in bytes.

It contains no character set, and comparison and sorting are based on the numeric value of the bytes.

If the maximum length is exceeded, and SQL strict mode is not enabled , the extra characters will be dropped with a warning. If strict mode is enabled, an error will occur.

BINARY values are right-padded with 0x00 (the zero byte) to the specified length when inserted. The padding is not removed on select, so this needs to be taken into account when sorting and comparing, where all bytes are significant. The zero byte, 0x00 is less than a space for comparison purposes.

Examples

Inserting too many characters, first with strict mode off, then with it on:

CREATE TABLE bins (a BINARY(10));

INSERT INTO bins VALUES('12345678901');
Query OK, 1 row affected, 1 warning (0.04 sec)

SELECT * FROM bins;
+------------+
| a          |
+------------+
| 1234567890 |
+------------+

SET sql_mode='STRICT_ALL_TABLES';

INSERT INTO bins VALUES('12345678901');
ERROR 1406 (22001): Data too long for column 'a' at row 1

Sorting is performed with the byte value:

TRUNCATE bins;

INSERT INTO bins VALUES('A'),('B'),('a'),('b');

SELECT * FROM bins ORDER BY a;
+------+
| a    |
+------+
| A    |
| B    |
| a    |
| b    |
+------+

Using CAST to sort as a CHAR instead:

SELECT * FROM bins ORDER BY CAST(a AS CHAR);
+------+
| a    |
+------+
| a    |
| A    |
| b    |
| B    |
+------+

The field is a BINARY(10), so padding of two '\0's are inserted, causing comparisons that don't take this into account to fail:

TRUNCATE bins;

INSERT INTO bins VALUES('12345678');

SELECT a = '12345678', a = '12345678\0\0' from bins;
+----------------+--------------------+
| a = '12345678' | a = '12345678\0\0' |
+----------------+--------------------+
|              0 |                  1 |
+----------------+--------------------+

See Also

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