pub unsafe trait OdbcType<'a>: Sized {
fn sql_data_type() -> SqlDataType;
fn c_data_type() -> SqlCDataType;
fn convert(_: &'a [u8]) -> Self;
fn column_size(&self) -> SQLULEN;
fn value_ptr(&self) -> SQLPOINTER;
fn decimal_digits(&self) -> SQLSMALLINT { ... }
}