code: func (f *ParameterField) TypePrecisionScale() (int64, int64, bool) {
  	if f.tc.isDecimalType() {
  		return int64(f.length), int64(f.fraction), true
  	}
  	return 0, 0, false
  }
docs: // TypePrecisionScale returns the type precision and scale (decimal types) of the field.
  // see https://golang.org/pkg/database/sql/driver/#RowsColumnTypePrecisionScale