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MySQL Data Types - Data Length

Reference this page http://dev.mysql.com/doc/refman/5.0/en/data-types.html, and in particular, the storage requirement page http://dev.mysql.com/doc/refman/5.0/en/storage-requirements.html

 

Storage Requirements for String Types

In the following table, M represents the declared column length in characters for non-binary string types and bytes for binary string types. L represents the actual length in bytes of a given string value.

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
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)