return m.DB.Migrator().CreateConstraint(value, constraint)
		}
		return nil
	})
}

// ColumnTypes return columnTypes []gorm.ColumnType and execErr error
func (m Migrator) ColumnTypes(value interface{}) ([]gorm.ColumnType, error) {
	columnTypes := make([]gorm.ColumnType, 0)
	execErr := m.RunWithValue(value, func(stmt *gorm.Statement) (err error) {

func prepareValues(values []interface{}, db *DB, columnTypes []*sql.ColumnType, columns []string) {
	if db.Statement.Schema != nil {
		for idx, name := range columns {
			if field := db.Statement.Schema.LookUpField(name); field != nil {
				values[idx] = reflect.New(reflect.PtrTo(field.FieldType)).Interface()
				continue
			}
			values[idx] = new(interface{})
		}
	} else if len(columnTypes) > 0 {
		for idx, columnType := range columnTypes {

	NewValuePool           FieldNewValuePool

	// In some db (e.g. MySQL), Unique and UniqueIndex are indistinguishable.
	// When a column has a (not Mul) UniqueIndex, Migrator always reports its gorm.ColumnType is Unique.
	// It causes field unnecessarily migration.
	// Therefore, we need to record the UniqueIndex on this column (exclude Mul UniqueIndex) for MigrateColumnUnique.
	UniqueIndex string
}