Question

我有3张桌子。订单，订单行和商店。在Order表中具有StoreId，这是Stores表的外键，在Orderlines表中具有OrderId，是Order表的外键。我只需要获取字段Order.OrderId，Order.WarehouseOrderId，Store.StoreName和每个订单的订单行数。所以目前这是我的实现：

public List<Order> GetOrdersDashboardWithoutStatus1(SearchDashboardCriteria cri)
{
    using (var ctx = CreateDbContext())
    {
        var orders = (from items in ctx.Orders select items);
        if (cri.MerchantId != 0)
        {
            orders = orders.Where(x => x.Store.MerchantId == cri.MerchantId);
        }

        return orders.Where(x => (DbFunctions.TruncateTime(x.DateImported) >= DbFunctions.TruncateTime(cri.StartDate))
                && (DbFunctions.TruncateTime(x.DateImported) <= DbFunctions.TruncateTime(cri.EndDate)))
                 .Include(x => x.Store).Include(x => x.OrderLines).ToList();
    }
}

尽管当前实现可以正常运行，但是性能却很慢，有时会出现超时错误，因为一条记录可能有30K +订单。

Answer 1

您可以尝试这样的事情

using (var ctx = CreateDbContext())
{
            var orders = (from x in ctx.Orders 
                          where x.Store.MerchantId == cri.MerchantId
                          && add your other where condition
                          select NewDataModel
                          {
                            orderId = x.OrderId,
                            wareHouse = x.WarehouseOrderId,
                            storeName = x.Store.StoreName
                          }).ToArray();

}

匿名投影或自定义模型的投影仅检索投影中包含的列。

它将是Select * from Orders ...而不是Select OrderId,WareHouseOrderId from Orders

如果您的用例支持，也可以尝试分页(Take,skip)。 Similar answer for anonymous projection

从其他表格中选择字段

1 个答案: