MigrateColumn(dst interface{}, field *schema.Field, columnType ColumnType) error
	// MigrateColumnUnique migrate column's UNIQUE constraint, it's part of MigrateColumn.
	MigrateColumnUnique(dst interface{}, field *schema.Field, columnType ColumnType) error
	HasColumn(dst interface{}, field string) bool
	RenameColumn(dst interface{}, oldName, field string) error
	ColumnTypes(dst interface{}) ([]ColumnType, error)

	// Views

					parseCheckConstraints = stmt.Schema.ParseCheckConstraints()
				)
				for _, dbName := range stmt.Schema.DBNames {
					var foundColumn gorm.ColumnType

					for _, columnType := range columnTypes {
						if columnType.Name() == dbName {
							foundColumn = columnType
							break
						}
					}

					if foundColumn == nil {
						// not found, add column

					t.Fatalf("column name type should be correct, name: %v, length: %v, expects: %v, column: %#v",
						columnType.Name(), columnType.DatabaseTypeName(), dataType, columnType)
				}
				if length, ok := columnType.Length(); !ok || length != 100 {
					t.Fatalf("column name length should be correct, name: %v, length: %v, expects: %v, column: %#v",
						columnType.Name(), length, 100, columnType)
				}

// "INT", and "BIGINT".
func (ct ColumnType) DatabaseTypeName() string {
	if ct.DataTypeValue.Valid {
		return ct.DataTypeValue.String
	}
	return ct.SQLColumnType.DatabaseTypeName()
}

// ColumnType returns the database type of the column. like `varchar(16)`
func (ct ColumnType) ColumnType() (columnType string, ok bool) {
	return ct.ColumnTypeValue.String, ct.ColumnTypeValue.Valid
}

	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 {

pkg database/sql, method (*ColumnType) DatabaseTypeName() string
pkg database/sql, method (*ColumnType) DecimalSize() (int64, int64, bool)
pkg database/sql, method (*ColumnType) Length() (int64, bool)
pkg database/sql, method (*ColumnType) Name() string
pkg database/sql, method (*ColumnType) Nullable() (bool, bool)
pkg database/sql, method (*ColumnType) ScanType() reflect.Type

}

// GetDBConnector SQL db connector
type GetDBConnector interface {
	GetDBConn() (*sql.DB, error)
}

// Rows rows interface
type Rows interface {
	Columns() ([]string, error)
	ColumnTypes() ([]*sql.ColumnType, error)
	Next() bool
	Scan(dest ...interface{}) error
	Err() error
	Close() error
}

type ErrorTranslator interface {
	Translate(err error) error

	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
}