func (ct ColumnType) ColumnType() (columnType string, ok bool) {
	return ct.ColumnTypeValue.String, ct.ColumnTypeValue.Valid
}

// PrimaryKey returns the column is primary key or not.
func (ct ColumnType) PrimaryKey() (isPrimaryKey bool, ok bool) {
	return ct.PrimaryKeyValue.Bool, ct.PrimaryKeyValue.Valid
}

// AutoIncrement returns the column is auto increment or not.