}

	if constraint.OnUpdate != "" {
		sql += " ON UPDATE " + constraint.OnUpdate
	}

	foreignKeys := make([]interface{}, 0, len(constraint.ForeignKeys))
	for _, field := range constraint.ForeignKeys {
		foreignKeys = append(foreignKeys, clause.Column{Name: field.DBName})
	}

	references := make([]interface{}, 0, len(constraint.References))
	for _, field := range constraint.References {

			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 {

}

// ToQueryValues to query values
func ToQueryValues(table string, foreignKeys []string, foreignValues [][]interface{}) (interface{}, []interface{}) {
	queryValues := make([]interface{}, len(foreignValues))
	if len(foreignKeys) == 1 {
		for idx, r := range foreignValues {
			queryValues[idx] = r[0]
		}

		return clause.Column{Table: table, Name: foreignKeys[0]}, queryValues
	}

	}

	for _, ref := range rel.References {
		fkNil[ref.ForeignKey.DBName] = nil

		if ref.OwnPrimaryKey && ref.PrimaryKey != nil {
			ownerPKNames = append(ownerPKNames, ref.PrimaryKey.DBName)
			primaryColumns = append(primaryColumns, clause.Column{Name: ref.PrimaryKey.DBName})
			foreignColumns = append(foreignColumns, clause.Column{Name: ref.ForeignKey.DBName})
		} else if !ref.OwnPrimaryKey && ref.PrimaryKey != nil {