mysql二进制类型

由于之前网站使用第三方登录，QQ昵称比较特殊，所以用二进制的字段类型存储。

mysql二进制类型有：

BINARY

VARBINARY

TINYBLOB, BLOB, MEDIUMBLOB, and LONGBLOB

顺便列一下各种数据类型的存储范围：

Storage Requirements for Numeric Types

Data Type

Storage Required

TINYINT

1 byte

SMALLINT

2 bytes

MEDIUMINT

3 bytes

INT, INTEGER

4 bytes

BIGINT

8 bytes

FLOAT(_`p`_)

4 bytes if 0 <= p <= 24, 8 bytes if 25 <= p <= 53

FLOAT

4 bytes

DOUBLE [PRECISION], REAL

8 bytes

DECIMAL(_`M`_,_`D`_), NUMERIC(_`M`_,_`D`_)

Varies; see following discussion

BIT(_`M`_)

approximately (M+7)/8 bytes

Storage Requirements for Date and Time Types

Data Type

Storage Required Before MySQL 5.6.4

Storage Required as of MySQL 5.6.4

YEAR

1 byte

1 byte

DATE

3 bytes

3 bytes

TIME

3 bytes

3 bytes + fractional seconds storage

DATETIME

8 bytes

5 bytes + fractional seconds storage

TIMESTAMP

4 bytes

4 bytes + fractional seconds storage

Storage Requirements for String Types

Data Type

Storage Required

CHAR(_`M`_)

M × w bytes, 0 <= _`M`_ <= 255, where w is the number of bytes required for the maximum-length character in the character set. SeeSection 15.2.6.7, “Physical Row Structure” for information about CHAR data type storage requirements for InnoDB tables.

BINARY(_`M`_)

M bytes, 0 <= _`M`_ <= 255

VARCHAR(_`M`_), VARBINARY(_`M`_)

L + 1 bytes if column values require 0 − 255 bytes, L + 2 bytes if values may require more than 255 bytes

TINYBLOB, TINYTEXT

L + 1 bytes, where L < 28

BLOB, TEXT

L + 2 bytes, where L < 216

MEDIUMBLOB, MEDIUMTEXT

L + 3 bytes, where L < 224

LONGBLOB, LONGTEXT

L + 4 bytes, where L < 232

ENUM('_`value1`_','_`value2`_',...)

1 or 2 bytes, depending on the number of enumeration values (65,535 values maximum)

SET('_`value1`_','_`value2`_',...)

1, 2, 3, 4, or 8 bytes, depending on the number of set members (64 members maximum)

参考：http://dev.mysql.com/doc/refman/5.7/en/data-types.html