Sams Teach Yourself MySQL

CHAR and VARCHAR

CHAR and VARCHAR are character data types. You give a maximum length in parentheses when specifying the column; if you attempt to insert a value longer than the maximum length, it is truncated.

A CHAR column has a fixed length, and values shorter than the maximum length are padded with spaces when stored. When you retrieve the value from a CHAR column, however, the trailing spaces are removed. The storage requirement for a CHAR column is simply 1 byte per character in the padded stored value.

A VARCHAR column has a variable length. Its storage requirement for each row depends on the length of the data item it contains—1 byte for each character is required, plus 1 byte that stores the value’s length.

You might use a CHAR(2) column ...