func (f *ResultField) TypeLength() (int64, bool) {
	if f.tc.isVariableLength() {
		return int64(f.length), true
	}
	return 0, false
}
func (f *ResultField) TypeLength() (int64, bool) {
	if f.tc.isVariableLength() {
		return int64(f.length), true
	}
	return 0, false
}
// TypeLength returns the type length of the field.
// see https://golang.org/pkg/database/sql/driver/#RowsColumnTypeLength