type ColumnStruct2 struct {
		gorm.Model
		Name  string `gorm:"size:100"`
		Code  string `gorm:"unique;comment:my code2;default:hello"`
		Code2 string `gorm:"unique"`
		// Code3 string
	}

	if err := DB.Table("column_structs").Migrator().AlterColumn(&ColumnStruct{}, "Name"); err != nil {
		t.Fatalf("no error should happened when alter column, but got %v", err)
	}