SQL 到 Linq 实体

Posted 2023-03-23

【中文标题】SQL 到 Linq 实体

【英文标题】：SQL to Linq-Entities

【发布时间】：2013-09-10 07:42:12

【问题描述】：

请帮我在 LINQ-Enitites 中转换这个 SQL 查询

select e.RowMeterialName,f.RowUnitName,*,isnull((b.Quantity - (Select SUM(a.Quantity) from PurchaseDetail a
                    join PurchaseMaster c on a.PurchaseId=c.PurchaseId
                    where a.RawMetId=b.RawMetrialId and c.PurchaseOrderId=b.PurchaseOrderId)),b.Quantity) as Remain 
                    from PurchaseOrderDetail b
                    join RawMeterialMaster e on b.RawMetrialId=e.RawMetId
                    join RawUnitMaster f on e.RawUnitId=f.RowUnitId
                    where b.PurchaseOrderId=@PurchaseOrderId

请帮帮我。

【问题讨论】：

请不要只删除 SQL 并要求转换。至少显示一个类模型，以便导航属性和关联的多样性是可见的。

SO 在粘贴图像之前要求 10 个回购点。

【参考方案1】：

这是一个长镜头，但你可以试试：

PurchaseDetail
.Join
(
    PurchaseMaster,
    x=>x.PurchaseId,
    x=>x.PurchaseId,
    (detail,master)=>new detail,master
)
.Join
(
    PurchaseOrderMaster,
    x=>x.PurchaseOrderId,
    x=>x.PurchaseOrderId,
    (joined,ordermaster)=>newdetail=joined.detail,master=joined.master,ordermaster
)
.Select
(
    x=>
    newdetail.Quantity,detail.RawMetId
)
.GroupBy(x=>x.RawMetId)
.Select
(
    x=>
    new
    
        RawMetId=x.Key,
        Quantity=x.Sum(z=>z.Quantity)
    
)
.Join
(
    PurchaseOrderDetail,
    x=>x.RawMetrialId,
    x=>x.RawMetId,
    (subquery,orderdetail)=>newsubquery,Remain=subquery.Quantity - orderdetail.Quantity
)

【参考方案2】：

谢谢大家，但我找到了这个查询的结果

from b in db.PurchaseOrderDetails
                        select new
                        
                            b.RawMeterialMaster.RowMeterialName,
                            PurOrderDetailId = b.PurOrderDetailId,
                            PurchaseOrderId = b.PurchaseOrderId,
                            RawMetrialId = b.RawMetrialId,
                            DueOn = b.DueOn,
                            Quantity = b.Quantity,
                            ItemRate = b.ItemRate,
                            MetrialUnitsId = b.MetrialUnitsId,
                            Remark = b.Remark,
                            RowUnitName = b.RawMeterialMaster.RawUnitMaster.RowUnitName,
                            ReOrderQuantity = (decimal?)b.RawMeterialMaster.ReOrderQuantity,
                            Remain = ((System.Decimal?)b.Quantity -
                              (from a in db.PurchaseDetails
                               where
                                a.RawMetId == b.RawMetrialId &&
                                a.PurchaseMaster.PurchaseOrderId == b.PurchaseOrderId
                               select new
                               
                                   a.Quantity
                               ).Sum(p => p.Quantity) ?? (System.Decimal?)b.Quantity)
                        ;

【讨论】：

如果有人想将 SQL 转换为 LinQ，请使用第三方工具 Linqer 和 LinqPad。这些非常有用。感谢陈快乐。