Method order_by

src/query/helper.rs:604–610

Add an order_by expression ``` use sea_orm::{entity::*, query::*, tests_cfg::cake, DbBackend}; assert_eq!( cake::Entity::find() .order_by(cake::Column::Id, Order::Asc) .order_by(cake::Column::Name, Order::Desc) .build(DbBackend::MySql) .to_string(), "SELECT `cake`.`id`, `cake`.`name` FROM `cake` ORDER BY `cake`.`id` ASC, `cake`.`name` DESC" ); ```

(mut self, col: C, ord: Order)

    /// );
    /// ```
    fn order_by<C>(mut self, col: C, ord: Order) -> Self
    where
        C: IntoSimpleExpr,
    {
        self.query().order_by_expr(col.into_simple_expr(), ord);
        self
    }

    /// Add an order_by expression (ascending)
    /// ```