我无法理解 Linq to Entities 中的左外连接计数。
我的查询是:
SELECT Locations.LocationId, Locations.LocationName, LocationPrizes.PrizeId, LocationPrizes.PrizeQuantity, Prizes.PrizeName, ISNULL(COUNT(WonPrizes.WonPrizeId), 0) AS WonPrizes
FROM Locations
INNER JOIN LocationPrizes ON Locations.LocationId = LocationPrizes.LocationId INNER JOIN Prizes ON LocationPrizes.PrizeId = Prizes.PrizeId
LEFT OUTER JOIN WonPrizes ON Locations.LocationId = WonPrizes.LocationId AND Prizes.PrizeId = WonPrizes.PrizeId
GROUP BY Locations.LocationId, Locations.LocationName, LocationPrizes.PrizeId, LocationPrizes.PrizeQuantity, Prizes.PrizeName
我的 Linq 是:
var locationPrizes = from l in context.Locations
select new
{
l.LocationId,
l.LocationName,
Prizes = from o in l.LocationPrizes
select new
{
o.PrizeId,
o.PrizeQuantity,
o.Prize.PrizeJson
}
};
我无法计算左外连接部分是否正常工作。任何指针?