So I have few tables and i want inner join it information two create
new object. But I have a little bit trouble.
One my table have connection one to many, and when linq request , it
give me more result than i want , he just copy information. I need
request something like this:
IPagedList<HelperListings> srch = (from l in db.gp_listing
where l.DateCreated > weekago
join lp in db.gp_listing_photo on l.Id equals lp.ListingId
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings { id = l.Id, HouseNumber = l.HouseNumber,ListingPrice = l.ListingPrice, PhotoUrl = lp.PhotoUrl.First(), AreaStateCode = loc.AreaStateCode }).ToList().ToPagedList(page ?? 1, 15);
PhotoUrl = lp.PhotoUrl.First() i need something like this but i don`t have any ideas how to do it. Need ur help guys.
UPDATE :
Responding to your comment, you have at least 2 options : 1. use group by and select only the first PhotoUrl from each group, or 2. don't join to gp_listing_photo table to avoid duplicated rows, and use subquery to get only the first PhotoUrl. Example for the latter :
IPagedList<HelperListings> srch =
(from l in db.gp_listing
where l.DateCreated > weekago
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings
{
id = l.Id,
HouseNumber = l.HouseNumber,
ListingPrice = l.ListingPrice,
PhotoUrl = (from lp in db.gp_listing_photo where l.Id = lp.ListingId select lp.PhotoUrl).FirstOrDefault(),
AreaStateCode = loc.AreaStateCode
}
).ToList().ToPagedList(page ?? 1, 15);
How about simply appending .Distinct() after your LINQ query to avoid duplicated data :
IPagedList<HelperListings> srch =
(from l in db.gp_listing
where l.DateCreated > weekago
join lp in db.gp_listing_photo on l.Id equals lp.ListingId
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings
{
id = l.Id,
HouseNumber = l.HouseNumber,
ListingPrice = l.ListingPrice,
PhotoUrl = lp.PhotoUrl,
AreaStateCode = loc.AreaStateCode
}
).Distinct().ToList().ToPagedList(page ?? 1, 15);
For Reference : LINQ Select Distinct with Anonymous Types
Related
If the person you are searching is a CIA emplyee, take his CIAJobs.EmployerID, otherwise select People.ID
SELECT
case when CIAJobs.EmployeeID IS NULL then People.ID
else CIAJobs.EmployerID
end
FROM [FMO].[People] AS p
LEFT JOIN [FMO].[CIAJobs] j
ON (p.ID = j.[EmployeeID])
AND (j.[relationshipType] = '25a8d79d-377e-4108-8c92-0ef9a2e1ab63')
where p.ID = '1b66e032-94b2-e811-96e0-f48c508e38a2' // id of person you search for
OR
j.[EmployeeID] = '1b66e032-94b2-e811-96e0-f48c508e38a2' // id of person you search for
I tried doing this in Linq:
var a = from l in People
join x in CIAJobs
on l.Id equals x.EmployeeID && x.RelationshipTypeGuid equals Guid.Parse('25a8d79d-377e-4108-8c92-0ef9a2e1ab63')
into gcomplex
from xx in gcomplex.DefaultIfEmpty()
select (xx.EmployeeID == null) ? l.EmployeeId : x.EmployerID;
var b = a.ToList();
why does the query show an error because of this chunk: && x.RelationshipTypeGuid equals Guid.Parse('25a8d79d-377e-4108-8c92-0ef9a2e1ab63')
If I remove this part it shows no error.
Error is: operator && cannot be applied to operands of type Guid and Guid.
Can you help me correct the Linq query please logically and syntactically? Thank you.
You don't need join for multiple conditions in this scenario. Use this
var a = from l in People
join x in CIAJobs
.Where(z=>z.RelationshipTypeGuid
.Equals(Guid.Parse('25a8d79d-377e-4108-8c92-0ef9a2e1ab63')))
on l.Id equals x.EmployeeID
into gcomplex
from xx in gcomplex.DefaultIfEmpty()
select (xx.EmployeeID == null) ? l.EmployeeId : x.EmployerID;
var b = a.ToList();
But based on your problem statement this should do
var a = from l in People
join x in CIAJobs
on l.Id equals x.EmployeeID
into gcomplex
from xx in gcomplex.DefaultIfEmpty()
select (xx == null) ? l.EmployeeId : xx.EmployerID;
var b = a.ToList();
SELECT ra.ResidentID, ra.RoomID, r.Number, ra.StartDate, p.FacilityID
FROM(
SELECT ResidentID, MAX(StartDate) AS max_start
FROM RoomAssignments
GROUP BY ResidentID
) m
INNER JOIN RoomAssignments ra
ON ra.ResidentID = m.ResidentID
AND ra.StartDate = m.max_start
INNER JOIN Rooms r
ON r.ID = ra.RoomID
INNER JOIN Person p
ON p.ID = ra.ResidentID
inner join ComplianceStage cs
ON cs.Id = p.ComplianceStageID
ORDER BY ra.EndDate DESC
I'm trying to figure out how to convert this to C# using LINQ. I'm brand new with C# and LINQ and can't get my subquery to fire correctly. Any chance one of you wizards can turn the lights on for me?
Update-----------------
I think I've got the jist of it, but am having trouble querying for the max startdate:
var maxQuery =
from mra in RoomAssignments
group mra by mra.ResidentID
select new { mra.ResidentID, mra.StartDate.Max() };
from ra in RoomAssignments
join r in Rooms on ra.RoomID equals r.ID
join p in Persons on ra.ResidentID equals p.ID
where ra.ResidentID == maxQuery.ResidentID
where ra.StartDate == maxQuery.StartDate
orderby ra.ResidentID, ra.StartDate descending
select new {ra.ResidentID, ra.RoomID, r.Number, ra.StartDate, p.FacilityID}
Following my LINQ to SQL Recipe, the conversion is pretty straight forward if you just follow the SQL. The only tricky part is joining the range variable from the subquery for max start date to a new anonymous object from RoomAssignments that matches the field names.
var maxQuery = from mra in RoomAssignments
group mra by mra.ResidentID into mrag
select new { ResidentID = mrag.Key, MaxStart = mrag.Max(mra => mra.StartDate) };
var ans = from m in maxQuery
join ra in RoomAssignments on m equals new { ra.ResidentID, MaxStart = ra.StartDate }
join r in Rooms on ra.RoomID equals r.ID
join p in Persons on ra.ResidentID equals p.ID
join cs in ComplianceStage on p.ComplianceStageID equals cs.Id
orderby ra.EndDate descending
select new {
ra.ResidentID,
ra.RoomID,
r.Number,
ra.StartDate,
p.FacilityID
};
I try to make the following query using Account, Case and Activity entities :
*var findCases =
from a in context.AccountSet
join c in context.IncidentSet
on a.AccountId equals c.CustomerId.Id
join p in context.ActivityPointerSet
on c.Id equals p.RegardingObjectId.Id
select new
{
TicketNumber = c.TicketNumber,
IncidentId = c.IncidentId,
CreatedOn = c.CreatedOn,
StateCode = c.StateCode,
AccountName = a.Name
};*
The execution of this query gives the error:
AttributeFrom and AttributeTo must be either both specified or both ommited. You can not pass only one or the other. AttributeFrom: , AttributeTo: regardingobjectid
Any suggestion will be appreciated.
Regards.
Radu Antonache
Remove CasesForAccount from the query..
*var findCases =
from a in context.AccountSet
join c in context.IncidentSet
on a.AccountId equals c.CustomerId.Id
join p in context.ActivityPointerSet
on c.Id equals p.RegardingObjectId.Id
select new
{
TicketNumber = c.TicketNumber,
IncidentId = c.IncidentId,
CreatedOn = c.CreatedOn,
StateCode = c.StateCode,
AccountName = a.Name
};*
I am trying to reproduce a SQL query using a LINQ to Entities query. The following SQL works fine, I just don't see how to do it in LINQ. I have tried for a few hours today but I'm just missing something.
SELECT
h.ReqID,
rs.RoutingSection
FROM ReqHeader h
JOIN ReqRoutings rr ON rr.ReqRoutingID = (SELECT TOP 1 r1.ReqRoutingID
FROM ReqRoutings r1
WHERE r1.ReqID = h.ReqID
ORDER BY r1.ReqRoutingID desc)
JOIN ReqRoutingSections rs ON rs.RoutingSectionID = rr.RoutingSectionID
Edit***
I was able to get this working after looking at other examples including the one provided her by Miki. Here is the code that works for me:
First I created a query called route to hold the top record I needed to join to
var route = (from rr in context.ReqRoutings
where rr.ReqID == id
orderby rr.ID descending
select rr).Take(1);
I was then able to join to my requisitions table and the ReqRoutings lookup table
var header = (from h in context.ReqHeaders
join r in route on h.ID equals r.ReqID
join rs in context.ReqRoutingSections on r.RoutingSectionID equals rs.ID
where h.ID == id
select {ReqID = h.ID,
RoutingSection = rs.RoutingSection}
I am using Northwnd sample database
Customers,Orders,Employees table
Here I am getting top 1 order group by customer and order's employeeid
Please let me know If this is matching with your requirement or not
var ord = from o in NDC.Orders
orderby o.OrderID descending
group o by o.CustomerID into g
select new {CustomerID=g.Key,Order=g.OrderByDescending(s=>s.OrderID).First() };
var res1 = from o in ord
join emp in NDC.Employees
on o.Order.EmployeeID equals emp.EmployeeID into oemp
select new {Order=o.Order,employee=oemp };
Response.Write(res1.ToList().Count);
foreach (var order in res1)
{
Response.Write(order.Order.CustomerID + "," +
order.Order.OrderID + ","+
order.Order.EmployeeID+"<br/>");
}
// Above code is working .I have tried to convert your query to linq and replace your datacontext name with 'NDC'
var ord = from rr in NDC.ReqRoutings
orderby rr.ReqRoutingID descending
group rr by rr.ReqID into g
select new
{
ReqID = g.Key,
ReqRoutings = g.OrderByDescending(s => s.ReqRoutingID).First()
};
var res1 = from o in ord
join emp in NDC.ReqRoutingSections on o.ReqRoutings.RoutingSectionID
equals emp.RoutingSectionID into oemp
select new { ReqRoutings = o.ReqRoutings, employee = oemp };
Response.Write(res1.ToList().Count);
foreach (var order in res1)
{
Response.Write(order.ReqRoutings.ReqID + "," +
order.ReqRoutings.ReqRoutingID + "," +
order.ReqRoutings.RoutingSectionID + "<br/>");
}
Please let know if it is help you or not
I have a query that has the following
var myvar = from table in MyDataModel
where.....
select new MyModel
{
modelvar1 = ...,
modelvar2 = (from..... into anothervar)
}
What I want to do is have modelvar2 be a join between the result I currently get from anothervar with another table in MyDataModel.
Thanks
The parenthesis looks more like a subquery than a join. This is how you do a join.
Example tables from the AdventureWorks database.
using (DataClasses1DataContext context = new DataClasses1DataContext())
{
// If you have foreign keys correctly in your database you can
// join implicitly with the "dot" notation.
var myvar = from prod in context.Products
where prod.ListPrice < 10
select new
{
Name = prod.Name,
Category = prod.ProductSubcategory.ProductCategory.Name,
};
// If you don't have foreign keys you need to express the join
// explicitly like this
var myvar2 = from prod in context.Products
join prodSubCategory in context.ProductSubcategories
on prod.ProductSubcategoryID equals prodSubCategory.ProductSubcategoryID
join prodCategory in context.ProductCategories
on prodSubCategory.ProductCategoryID equals prodCategory.ProductCategoryID
where prod.ListPrice < 10
select new
{
Name = prod.Name,
Category = prodCategory.Name,
};
// If you REALLY want to do a subquery, this is how to do that
var myvar3 = from prod in context.Products
where prod.ListPrice < 10
select new
{
Name = prod.Name,
Category = (from prodSubCategory in context.ProductSubcategories
join prodCategory in context.ProductCategories
on prodSubCategory.ProductCategoryID equals prodCategory.ProductCategoryID
select prodCategory.Name).First(),
};
// If you want to get a list from the subquery you can do like this
var myvar4 = from prodCategory in context.ProductCategories
select new
{
Name = prodCategory.Name,
Subcategoreis = (from prodSubCategory in context.ProductSubcategories
where prodSubCategory.ProductCategoryID == prodCategory.ProductCategoryID
select new { prodSubCategory.ProductSubcategoryID, prodSubCategory.Name }).ToList(),
};
}
SELECT [t0].[OrderID], [t0].[CustomerID], [t0].[EmployeeID], [t0].[OrderDate], [t0].[RequiredDate], [t0].[ShippedDate], [t0].[ShipVia], [t0].[Freight], [t0].[ShipName], [t0].[ShipAddress], [t0].[ShipCity], [t0].[ShipRegion], [t0].[ShipPostalCode], [t0].[ShipCountry]
FROM [Orders] AS [t0]
INNER JOIN ([Order Details] AS [t1]
INNER JOIN [Products] AS [t2] ON [t1].[ProductID] = [t2].[ProductID]) ON [t0].[OrderID] = [t1].[OrderID]
can be write as
from o in Orders
join od in (
from od in OrderDetails join p in Products on od.ProductID equals p.ProductID select od)
on o.OrderID equals od.OrderID
select o