假设我有这个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.StaffFName
结果:
|StaffFName |TOTAL |Occupied|
-----------------------------------
|Jason |13 |1 |
|John Doe |9 |0 |
|Marry Jane |7 |2 |
这是我的数据库表:
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)
}
计划拥有Occupied = NewGroup.Sum(b => b.Quantity)
,但当我尝试将b
指向quantity
表中的Booking
列时,它会显示错误(红线),我认为来自group ps by ps.StaffFName into NewGroup
的问题使其可用于PromotionSlot
表而不是Booking
表。但我完全不知道如何解决这个问题!
答案 0 :(得分:2)
根据您的SQL
查询,您需要的是Distinct
个量和Sum
个。
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()
}