// Expr returns clause.Expr, which can be used to pass SQL expression as params
func Expr(expr string, args ...interface{}) clause.Expr {
	return clause.Expr{SQL: expr, Vars: args}
}

// SetupJoinTable setup join table schema
func (db *DB) SetupJoinTable(model interface{}, field string, joinTable interface{}) error {
	var (
		tx                      = db.getInstance()
		stmt                    = tx.Statement