C# LINQ左联接和GroupBy
假设我有一个SQL查询:C# LINQ左联接和GroupBy,c#,linq-to-entities,C#,Linq To Entities,假设我有一个SQL查询: SELECT PromotionSlot.StaffFName, SUM(PromotionSlot.Max_Occupancy) AS TOTAL, SUM(DISTINCT(Booking.Quantity)) AS Occupied From PromotionSlot LEFT JOIN Booking ON PromotionSlot.StaffID=Booking.StaffID GROUP BY PromotionSlot.
SELECT
PromotionSlot.StaffFName,
SUM(PromotionSlot.Max_Occupancy) AS TOTAL,
SUM(DISTINCT(Booking.Quantity)) AS Occupied
From PromotionSlot
LEFT JOIN Booking
ON PromotionSlot.StaffID=Booking.StaffID
GROUP BY PromotionSlot.StaffFName
结果:
|StaffFName |TOTAL |Occupied|
-----------------------------------
|Jason |13 |1 |
|John Doe |9 |0 |
|Marry Jane |7 |2 |
这是我的DB表:
PromotionSlot TABLE: ID(PK),Max_Occupancy,StaffFName..., StaffID(FK)
Booking TABLE: ID(PK), Quantity...,StaffID(FK)
如何将其翻译成LINQ?这是我的尝试:
var staffData =
(from ps in dc.PromotionSlots
join b in dc.Bookings on ps.StaffID = b.StaffID
group ps by ps.StaffFName into NewGroup
select new dataView
{
StaffFName = NewGroup.Key,
Total = NewGroup.Sum(a => a.Max_Occupancy),
//problem:
//Occupied = NewGroup.Sum(b => b.Quantity)
}
计划使用
occumped=NewGroup.Sum(b=>b.Quantity)
但当我尝试将b
指向Booking
表中的Quantity
列时,它显示错误(红线)我认为问题来自于groupps by ps.StaffFName to NewGroup
使其可用于PromotionSlot
表,而不是Booking
表。但我完全不知道如何解决这个问题 根据您的SQL
查询,您需要的是获取Distinct
数量和Sum
它们
var staffData =
(from ps in dc.PromotionSlots
join b in dc.Bookings on ps.StaffID = b.StaffID into slots
from slot in slots.DefaultIfEmpty()
group new {ps, slot} by ps.StaffFName into NewGroup
select new dataView
{
StaffFName = NewGroup.Key,
Total = NewGroup.Sum(a => a.ps!=null? a.ps.Max_Occupancy: 0),
//problem:
Occupied = NewGroup.Select(x=>x.slot.Quantity).Distinct().Sum()
}
根据您的
SQL
查询,您需要的是获取Distinct
量化和Sum
它们
var staffData =
(from ps in dc.PromotionSlots
join b in dc.Bookings on ps.StaffID = b.StaffID into slots
from slot in slots.DefaultIfEmpty()
group new {ps, slot} by ps.StaffFName into NewGroup
select new dataView
{
StaffFName = NewGroup.Key,
Total = NewGroup.Sum(a => a.ps!=null? a.ps.Max_Occupancy: 0),
//problem:
Occupied = NewGroup.Select(x=>x.slot.Quantity).Distinct().Sum()
}
当尝试键入
x=>x.
时,它仍然只显示ps
表列,而不是b
表。您需要将两个实体groupnew{ps,b}按ps.StaffFName分组到NewGroup
@J4X中。现在我可以在选择new
中搜索两个表,但仍然不正确。第一个Sum
应该使用类似lambda的a=>a.ps.Max_Coccupancy
,第二个应该有x=>x.b.Quantity
。当尝试键入x=>x.
时,它仍然只显示ps
表列,而不是b
表。您需要对这两个实体进行分组对新的{ps,b}通过ps.StaffFName进入新组
@J4X请现在检查。现在我可以在选择新
中搜索两个表,但仍然不正确。第一个Sum
应使用类似于a=>a.ps.Max_Coccupancy
的lambda,第二个应具有x=>x.b.Quantity
。