Asp.net mvc 3 如何用foreach更好地编写此LINQ
我在用实体框架进行MVC3项目。我对foreach有一个LINQ查询。一切都很好。但当数据量增加时,我就面临性能问题。我对林克没有多少经验。所以我无法解决我的问题。请看一下我的代码,并为我提供更好的建议 代码Asp.net mvc 3 如何用foreach更好地编写此LINQ,asp.net-mvc-3,c#-4.0,linq-to-entities,Asp.net Mvc 3,C# 4.0,Linq To Entities,我在用实体框架进行MVC3项目。我对foreach有一个LINQ查询。一切都很好。但当数据量增加时,我就面临性能问题。我对林克没有多少经验。所以我无法解决我的问题。请看一下我的代码,并为我提供更好的建议 代码 List<int> RouteIds = db.Cap.Where(asd => asd.Type == 3).Select(asd => asd.UserId).ToList(); var UsersWithRoutingId =
List<int> RouteIds = db.Cap.Where(asd => asd.Type == 3).Select(asd => asd.UserId).ToList();
var UsersWithRoutingId = (from route in db.RoutingListMembers
where RouteIds.Contains(route.RoutingListId.Value) && route.User.UserDeptId == Id
select
new RoutingWithUser
{
UserId = route.UserId,
RoutingId = route.RoutingListId
});
var ListRouteValue = (from cap in db.CareAllocationPercents
where cap.Type == 3
select new UserWithDeptId
{
Year = (from amt in db.CareAllocations where amt.CareItemId == cap.CareItemId select amt.Year).FirstOrDefault(),
UserId = cap.UserId,
UserDeptId = (from userdept in db.Users where userdept.Id == cap.UserId select userdept.UserDeptId).FirstOrDefault(),
});
List<UserWithDeptId> NewRouteList = new List<UserWithDeptId>();
ListRouteValue = ListRouteValue.Where(asd => asd.Year == Year);
foreach (var listdept in ListRouteValue)
{
foreach (var users in UsersWithRoutingId)
{
if (users.RoutingId == listdept.UserId)
{
UserWithDeptId UserwithRouteObj = new UserWithDeptId();
UserwithRouteObj.UserId = users.UserId;
UserwithRouteObj.Year = listdept.Year;
UserwithRouteObj.UserDeptId = db.Users.Where(asd => asd.Id == users.UserId).Select(asd => asd.UserDeptId).FirstOrDefault();
NewRouteList.Add(UserwithRouteObj);
}
}
}
NewRouteList = NewRouteList.Where(asd => asd.UserDeptId == Id).ToList();
List RouteIds=db.Cap.Where(asd=>asd.Type==3);
var UsersWithRoutingId=(来自db.RoutingListMembers中的路由
其中RouteIds.Contains(route.RoutingListId.Value)和&route.User.UserDeptId==Id
选择
新路由与用户
{
UserId=route.UserId,
RoutingId=route.RoutingListId
});
var ListRouteValue=(来自db.CareAllocationPercents中的cap
其中cap.Type==3
选择新用户WithDeptid
{
年份=(从db.careeAllocations中的金额,其中amt.careeItemId==cap.careeItemId选择amt.Year)。FirstOrDefault(),
UserId=cap.UserId,
UserDeptId=(从db.Users中的userdept开始,其中userdept.Id==cap.UserId选择userdept.UserDeptId)。FirstOrDefault(),
});
List NewRouteList=新列表();
ListRouteValue=ListRouteValue.Where(asd=>asd.Year==Year);
foreach(ListRouteValue中的var listdept)
{
foreach(UsersWithRoutingId中的var用户)
{
if(users.RoutingId==listdept.UserId)
{
UserWithDeptId UserwithRouteObj=新用户withdeptid();
UserwithRouteObj.UserId=users.UserId;
UserwithRouteObj.Year=列表部门年份;
UserwithRouteObj.UserDeptId=db.Users.Where(asd=>asd.Id==Users.UserId)。选择(asd=>asd.UserDeptId.FirstOrDefault();
添加(UserwithRouteObj);
}
}
}
NewRouteList=NewRouteList.Where(asd=>asd.UserDeptId==Id.ToList();
谢谢,您必须在第一个语句中使用join。如何做到这一点的示例如下:我有一些想法要告诉你: 第一: 注意在linq查询中完成where-close,以获得所需的内容。 使用Linq on集合,可以删除一个foreach循环。我不知道结局,但我试着给你写点东西:
var UsersWithRoutingId = (from route in db.RoutingListMembers
where RouteIds.Contains(route.RoutingListId.Value) && route.User.UserDeptId == Id
select
new RoutingWithUser
{
UserId = route.UserId,
RoutingId = route.RoutingListId
});
var ListRouteValue = (from cap in db.CareAllocationPercents
where cap.Type == 3
select new UserWithDeptId
{
Year = (from amt in db.CareAllocations
where amt.CareItemId == cap.CareItemId && amt.Year == Year
select amt.Year).FirstOrDefault(),
UserId = cap.UserId,
UserDeptId = (from userdept in db.Users
where userdept.Id == cap.UserId && userdept.UserDeptId == Id
select userdept.UserDeptId).FirstOrDefault(),
});
List<UserWithDeptId> NewRouteList = new List<UserWithDeptId>();
foreach (var listdept in ListRouteValue)
{
var user = UsersWithRoutingId.Where(uwri => uwri.RoutingId == listdept.UserId).FirstOrDefault();
if (user != null)
{
NewRouteList.Add(new UserWithDeptId { UserId=user.UserId, Year=listdept.Year, UserDeptId=listdept.UserDeptId });
}
}
return NewRouteList
var userswithroutinggid=(来自db.RoutingListMembers中的路由
其中RouteIds.Contains(route.RoutingListId.Value)和&route.User.UserDeptId==Id
选择
新路由与用户
{
UserId=route.UserId,
RoutingId=route.RoutingListId
});
var ListRouteValue=(来自db.CareAllocationPercents中的cap
其中cap.Type==3
选择新用户WithDeptid
{
年份=(以db.1为单位的金额)
其中amt.CareItemId==cap.CareItemId&&amt.Year==Year
选择金额年份)。FirstOrDefault(),
UserId=cap.UserId,
UserDeptId=(来自数据库Users中的userdept
其中userdept.Id==cap.UserId&&userdept.UserDeptId==Id
选择userdept.UserDeptId).FirstOrDefault(),
});
List NewRouteList=新列表();
foreach(ListRouteValue中的var listdept)
{
var user=UsersWithRoutingId.Where(uwri=>uwri.RoutingId==listdept.UserId).FirstOrDefault();
如果(用户!=null)
{
NewRouteList.Add(new UserWithDeptId{UserId=user.UserId,Year=listdept.Year,UserDeptId=listdept.UserDeptId});
}
}
返回新路线列表
这对你合适吗?
(我不轮询db.user表,假设listdept中的表是好的,那么就为NewRouteList获取UserDeptId)
第二:
注意实体数据加载,如果您有带外键的表,如果不需要同时加载表的子级,请注意删除延迟加载。想象外键指向其他表的多个表的增益。
编辑:
这里有一个链接可以解释这一点: