[英]How to translate Linq/SQL to Lambda in c#
如何将下面的 Linq 代码转换为 Lambda 类型的查询?
var domainModel = (
from Hosps in _ctx.Hospital
from Room in _ctx.SickRoom
.Where(x => x.HospitalId == Hosps.HospitalId)
.GroupBy(x => x.HospitalId)
.Select(x => new
{
HospitalId = x.Key,
NumberOfFloors = x.Max(y => y.FloorId),
NumberOfRooms = x.Count()
})
.OrderBy(x => x.HospitalId)
select new
{
HospitalId = Hosps.HospitalId,
City = Hosps.City,
HospitalImage = Hosps.HospitalImage,
NumberOfFloors = Room.NumberOfFloors,
NumberOfApartments = Room.NumberOfRooms
}
).ToList();
如果有帮助,上面的 Linq 表达式的 SQL 查询是:
SELECT [r].[HospitalId]
,[r].[City]
,[r].[HospitalImage]
,[t].[c] AS [NumberOfFloors]
,[t].[c0] AS [NumberOfRooms]
FROM [Hospital] AS [r]
INNER JOIN (
SELECT [a].[HospitalId], MAX([a].[FloorId]) AS [c], COUNT(*) AS [c0]
FROM [SickRoom] AS [a]
GROUP BY [a].[HospitalId]
) AS [t] ON [r].[HospitalId] = [t].[HospitalId]
假设你有一个适当的 model 考虑到关系,它会像:
var domainModel = _ctx.Hospital.Select(h =>
new
{
HospitalId = h.HospitalId,
City = h.City,
HospitalImage = h.HospitalImage,
NumberOfFloors = h.SickRooms.Max(sr => sr.FloorId),
NumberOfApartments = h.SickRooms.Count()
})
.ToList();
请注意,您的 SQL 表明在您的 model 中有一个到医院病房 (h.SickRooms) 的导航。
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