Develop Reference

how to apply join or innerquery to connect two table

Here MyChildTable contains only id and the parent table contains id + name.
I have written a query to fetch the existing data from the table
await _dbContext.MyChildTable
.Where(c => c.CustomerId == **(select customerid from tableParent where customername= reqcustomername)**
Here i want to match customerId with the matching customer id from the second table ie tableParent.How to replace the query in to linq to get the proper record.select customerid from tableParent where customername= reqcustomername i want to replace this selection

I don't understand what you mean
so my maybe answer error
LINQ
using (entity entityData = new entity())
{
var checkqry2 = from T1 in entityData.MyChildTable.AsNoTracking()
join T2 in entityData.tableParent on
T1.CustomerId equals T2.customerid
where T1.customerid == "ID" && T2.customername == reqcustomername
group new { T2.customerid, T2.customername } by new { T1.customerid, T1.customername } into c
orderby c.Key.customerid
select new { customername=c.Key.customername,
customerid=c.Key.customerid,
};
}
you can try entity lambda
entity lambda
using (entity entityData = new entity())
{
var query1 = entityData.MyChildTable
.Join(entityData.tableParent , o => o.CustomerId , p => p.CustomerId , (o, p) => new
{
o.CustomerId,
p.customername,
}).Where(o => o.CustomerId == "123" && o.customername == "name").ToList();
}

Here I want to match customerId with the matching customer id from the
second table ie tableParent.How to replace the query in to linq to get
the proper record.select customerid from tableParent where
customername= reqcustomername i want to replace this selection
Well, lot of way around to handle this kind of scenario. Most easy and convenient way you could consider by using linq join or linq Enumerable which you can implement as following:
Sample Data:
var childList = new List<ChildTable>()
{
new ChildTable(){ Id =101,ChildName = "Child-A",CustomerId = 202},
new ChildTable(){ Id =102,ChildName = "Child-B",CustomerId = 203},
new ChildTable(){ Id =103,ChildName = "Child-C",CustomerId = 202},
new ChildTable(){ Id =104,ChildName = "Child-D",CustomerId = 204},
};
var parentList = new List<ParentTable>()
{
new ParentTable(){ Id =301,ParentName = "Parent-A",CustomerId = 202},
new ParentTable(){ Id =302,ParentName = "Parent-B",CustomerId = 202},
new ParentTable(){ Id =303,ParentName = "Parent-C",CustomerId = 203},
new ParentTable(){ Id =304,ParentName = "Parent-D",CustomerId = 205},
};
Linq Query:
Way One:
var findMatchedByCustId = from child in childList
where (from parent in parentList select parent.CustomerId)
.Contains(child.CustomerId)
select child;
Way Two:
var usingLinqJoin = (from parent in parentList
join child in childList on parent.CustomerId equals child.CustomerId
select parent).ToList().Distinct();
Output:
Note: If you need more information you could check our official document for Linq join and Linq Projction here.

GridView Only populating 1 result

I'm currently working to add Data to a GridView. The data comes from 2 tables that are on different databases. Currently I am able to populate the first entry, but it does not populate past that. here is the code:
void FillOrder(int inv)
{
var _ord = new OrdersContext();
var _pro = new ProductContext();
var qryOrder = (from o in _ord.OrderDetails
where o.InvNumberId == inv
select new
{
o.ProductID,
o.Quantity
}).ToList();
foreach (var order in qryOrder)
{
int prodID = order.ProductID;
int itemCount = qryOrder.Count;
var qryProducts = (from p in _pro.Products
where p.ProductID == prodID
select new
{
p.ProductID,
p.ProductName
}).ToList();
var results = (from t in qryOrder
join s in qryProducts
on t.ProductID equals prodID
select new
{
t.ProductID,
t.Quantity,
s.ProductName
}).ToList();
OrderItemList.DataSource = results;
OrderItemList.DataBind();
}
}
Can anyone help as to why it's only populating the first entry?

If the number of products involved is relatively small, (and since this query seems to be relate to one invoice, I would think that is true), then you can probably use something like the code below.
This is removing the loop, but the contains method will probably generate a SQL statement something like select ProductID, ProductName from products where productID in (,,,,,,) so may fail if the number of parameters is extremely large.
var _ord = new OrdersContext();
var _pro = new ProductContext();
var qryOrder = (from o in _ord.OrderDetails
where o.InvNumberId == inv
select new
{
o.ProductID,
o.Quantity
}).ToList();
// Get the productIDs
var productIDS = qryOrder.Select(o=>o.ProductID).Distinct().ToList();
// Get the details of the products used.
var qryProducts = (from p in _pro.Products
where productIDS.Contains(p.ProductID)
select new
{
p.ProductID,
p.ProductName
}).ToList();
// Combine the two in memory lists
var results = (from t in qryOrder
join s in qryProducts
on t.ProductID equals s.ProductID
select new
{
t.ProductID,
t.Quantity,
s.ProductName
}).ToList();
OrderItemList.DataSource = results;
OrderItemList.DataBind();

.Include() still queries database after a ToList()

I have the following View defined in my Context class, Entity Framework: I have added .Include() here, with the hopes that this will eliminate calls to database later.
public IQueryable<GeneralReportModel> vwGeneralReportItems
{
get
{
return from p in this.Patients.AsNoTracking().Include(p => p.Age) //Multiple includes added to include all properties on model
join fac in this.Facilities.AsNoTracking() on p.FacilityID equals fac.ID into fJoin
from f in fJoin.DefaultIfEmpty()
join userFac in this.UserFacilities.AsNoTracking() on p.FacilityID equals userFac.FacilityID into ufJoin
from uf in ufJoin.DefaultIfEmpty()
select new GeneralReportModel()
{
Patient = p,
//ReportIndex = ri,
Facility = f,
UserFacility = uf
};
}
}
I also have this function, which does some filtering on my select from the View:
private IQueryable<GeneralReportModel> generalReportQuery(ApplicationTypes.ReportParameterObject repParam)
{
var reportQuery = ReportHelper.GeneralReport_Source(this.DbContext, repParam, false);
reportQuery = ReportHelper.GeneralReport_FilterCriteria(this.DbContext, reportQuery, repParam);
// Lab confirmed - Extra Pulmonary
reportQuery = reportQuery.Where(rq =>
rq.Patient.TypeOfResistantTBConfirmation.Value == ApplicationTypes.ResistantTBConfirmationTypes.LABCONFIRMED.ToString() &&
rq.Patient.SiteOfDiseaseID != repParam.DatabaseSettingObject.SiteOfDiseaseID_ExtraPulmonary &&
rq.Patient.PatientCategoryID != ApplicationGlobal.GLBDATABASESETTINGOBJECT.PatientCategoryID_TransferIn);
return reportQuery;
}
The code below
var reportQueryMdr = reportQuery.Where(rq =>
rq.Patient.TypeOfResistantTB.Value == ApplicationTypes.ResistantTBTypes.MDR.ToString());
var list = reportQueryMdr.ToList();
foreach (var obj in list)
{
obj.ReportIndex = obj.Patient.getRecalculatedReportIndexFields(ApplicationGlobal.GLBDATABASESETTINGOBJECT);
}
reportQueryMdr = list.AsQueryable();
Still calls the Database for each iteration made over the list. How can I make this list entirely reside in memory, with all the Patient properties.

Linq Select Data based on a value in another table

I have the linq statements listed below and I want to restrict the records from one table based on the value in another table. This is the code I have which works:
using (context = new DocEntityConnection())
{
var Docs = context.tbDocsDetails.Where(md => md.IsCurrentDetails && md.tbDoc.StatusID == 9).ToList();
this.approves = context.tbDocApproves.ToList().Where(a => Docs.Select(x => x.DocID).ToList().Contains(a.DocID)).ToList();
return Docs.Select(md => GetDataItem(md)).ToList();
}
There is another table called tbDocStatus which has a DocId field too
I would like to only return records from tbDocDetails where tbDocdetails.DocId = tbDocStatus.DocId and tbDocStatus.StatusId = 4.
How would I add that to my code shown above?

That you need is a join
var Docs = from docDetail in context.tbDocsDetails
join docStatus in context.tbDocStatus
on docDetail.DocId = docStatus.DocId
where docStatus.StatusId == 4
select docDetail;

using (context = new DocEntityConnection())
{
var Docs = context.tbDocsDetails.Where(md => md.IsCurrentDetails && md.tbDoc.StatusID == 9).ToList();
var DocsFiltered = from d in Docs
join docStatus in context.tbDocStatus
on d.DocId equals docStatus.DocId
where docStatus.StatusId = 4
select d
this.approves = context.tbDocApproves.ToList().Where(a => Docs.Select(x => x.DocID).ToList().Contains(a.DocID)).ToList();
return DocsFiltered.Select(md => GetDataItem(md)).ToList();
}

LINQ Conditionally Add Join

I have a LINQ query where I'm trying to return data from 2 tables, but the tables that I join are conditional.
This is what I'd like to do:
if (teamType == "A"){
var query = from foo in context.People
join foo2 in context.PeopleExtendedInfoA
select foo;
}
else {
var query = from foo in context.People
join foo2 in context.PeopleExtendedInfoB
select foo;
}
Then later on I'm filtering the query down even further. I obviously can't set it up this way because I won't be able to access "query" outside the if block, but it shows what I'm trying to do. This is an example of what I'm trying to do later on with the query:
if (state != null)
{
query = query.Where(p => p.State == state);
}
if (query != null) {
var queryFinal = from foo in query
select new PeopleGrid()
{
Name = foo.Name,
Address = foo.Address,
Hobby = foo2.Hobby
}
}
What I'm trying to return is all the data from table foo and then one field from the joined table, but depending on the logic, the joined table will differ. Both PeopleExtendedInfoA and PeopleExtendedInfoB both have the columb 'Hobby', but I have no way to access 'Hobby' from the joined table and that's the only field I need from the joined table.
How would I go about doing this?

Does PeopleExtendedInfoA and PeopleExtendedInfoB inherits from the same base class? You could create a IQueryable<BaseClass> and let the linq provider solve it for you when you add the join. For sample:
IQueryable<BasePeople> basePeople;
if (teamType == "A")
basePeople = context.PeopleExtendedInfoA;
else
basePeople = context.PeopleExtendedInfoB;
var query = from foo in context.People
join foo2 in basePeople on foo.Id equals foo2.PeopleId
select new PeopleGrid()
{
Name = foo.Name,
Address = foo.Address,
Hobby = foo2.Hobby
};

try like this:
var queryFinal = from foo in query
where foo.State == state !=null ? state : foo.State
select new PeopleGrid()
{
Name = foo.Name,
Address = foo.Address,
Hobby = foo2.Hobby
}

You can query into an intermediate type that holds the relevant fields, or if the query is simple enough you can use anonymous types as seen below. The important part is that the Join calls both have the same return types ({ p.Name, a.Hobby } and { p.Name, b.Hobby } will both be the same anon type).
var baseQuery = context.People;
var joined = type == "A" ?
baseQuery.Join(PeopleExtendedInfoA,
p => p.Id,
a => a.PeopleId,
(p, a) => new { p, a.Hobby }) :
baseQuery.Join(PeopleExtendedInfoB,
p => p.Id,
b => b.PeopleId,
(p, b) => new { p, b.Hobby });
var result = joined.Select(x => new
{
x.p.Name,
x.p.Address,
// etc.
x.Hobby
};

I figured it out. Thanks everyone for all the replies, it got my brain working again and gave me some new ideas (even though I didn't directly take any of them) I realize I needed to do the join at the very end instead of the beginning that way I don't have to deal with filtering on different types. This is what I did:
var query = from foo in context.People
select foo;
if (state != null)
{
query = query.Where(p => p.State == state);
}
if (query != null) {
if (teamType == "A")
{
var queryFinal = from foo in query
join foo2 in context.PeopleExtendedInfoA
select new PeopleGrid()
{
Name = foo.Name,
Address = foo.Address,
Hobby = foo2.Hobby
}
}
else
{
var queryFinal = from foo in query
join foo2 in context.PeopleExtendedInfoB
select new PeopleGrid()
{
Name = foo.Name,
Address = foo.Address,
Hobby = foo2.Hobby
}
}
}