问题
If I want to store binary data (hash values) and they're always 128bytes long, what field type should I use? BLOBs are nice, but they aren't fixed width (and result in dynamic tables).. CHAR requires a charset.
回答1:
You can use BINARY, so BINARY(128).
Note that if you're storing character data, then the standard character set of the operating system is used to convert the character to it's byte value, so you'd have to take any cross-platform issues into consideration.
来源：https://stackoverflow.com/questions/2028949/ideal-field-type-for-fixed-width-binary-data