}
		}
	}

	// check comment
	if comment, ok := columnType.Comment(); ok && comment != field.Comment {
		// not primary key
		if !field.PrimaryKey {
			alterColumn = true
		}
	}

	if alterColumn {
		if err := m.DB.Migrator().AlterColumn(value, field.DBName); err != nil {
			return err
		}
	}

	GetTables() (tableList []string, err error)
	TableType(dst interface{}) (TableType, error)

	// Columns
	AddColumn(dst interface{}, field string) error
	DropColumn(dst interface{}, field string) error
	AlterColumn(dst interface{}, field string) error
	MigrateColumn(dst interface{}, field *schema.Field, columnType ColumnType) error
	// MigrateColumnUnique migrate column's UNIQUE constraint, it's part of MigrateColumn.