yval := reflect.ValueOf(y)
	if xval.Kind() == reflect.Ptr && xval.IsNil() ||
		yval.Kind() == reflect.Ptr && yval.IsNil() {
		return false
	}

	if valuer, ok := x.(driver.Valuer); ok {
		x, _ = valuer.Value()
	}
	if valuer, ok := y.(driver.Valuer); ok {
		y, _ = valuer.Value()
	}
	return reflect.DeepEqual(x, y)
}

func ToString(value interface{}) string {
	switch v := value.(type) {
	case string:

		}
	}

	var (
		name     string
		idx      = strings.Index(str, ",")
		settings = ParseTagSetting(str, ",")
	)

	// optimize match english letters and midline
	// The following code is basically called in for.
	// In order to avoid the performance problems caused by repeated compilation of regular expressions,
	// it only needs to be done once outside, so optimization is done here.

		callMethod(db, func(value interface{}, tx *gorm.DB) (called bool) {
			if db.Statement.Schema.BeforeSave {
				if i, ok := value.(BeforeSaveInterface); ok {
					called = true
					db.AddError(i.BeforeSave(tx))
				}
			}

			if db.Statement.Schema.BeforeCreate {
				if i, ok := value.(BeforeCreateInterface); ok {
					called = true
					db.AddError(i.BeforeCreate(tx))
				}
			}
			return called

		callMethod(db, func(value interface{}, tx *gorm.DB) (called bool) {
			if db.Statement.Schema.BeforeSave {
				if i, ok := value.(BeforeSaveInterface); ok {
					called = true
					db.AddError(i.BeforeSave(tx))
				}
			}

			if db.Statement.Schema.BeforeUpdate {
				if i, ok := value.(BeforeUpdateInterface); ok {
					called = true
					db.AddError(i.BeforeUpdate(tx))
				}
			}

			if field := stmt.Schema.LookUpField(name); field != nil {
				name = field.DBName
			}
		}

		return m.DB.Exec(
			"ALTER TABLE ? DROP COLUMN ?", m.CurrentTable(stmt), clause.Column{Name: name},
		).Error
	})
}

// AlterColumn alter value's `field` column' type based on schema definition
func (m Migrator) AlterColumn(value interface{}, field string) error {