primaryFields []*schema.Field
			foreignKeys   []string
			updateAttrs   = map[string]interface{}{}
			conds         []clause.Expression
		)

		for _, ref := range rel.References {
			if ref.PrimaryValue == "" {
				primaryFields = append(primaryFields, ref.PrimaryKey)
				foreignKeys = append(foreignKeys, ref.ForeignKey.DBName)
				updateAttrs[ref.ForeignKey.DBName] = nil
			} else {