Using this interface, you can implement a type handler that
will perform customized processing before parameters are set
on and after values are retrieved from the database.
Using a custom type handler you can extend
the framework to handle types that are not supported, or
handle supported types in a different way. For example,
you might use a custom type handler to implement proprietary
BLOB support (e.g. Oracle), or you might use it to handle
booleans using "Y" and "N" instead of the more typical 0/1.