We have two objects, Dates and ActiveEvents. Want to perform inner join on these with less than or equal to condition in linq. Same as ref of below SQL where consider #Tables are C# objects
Select A. from #Activities A
Inner Join #Dates D ON A.ActivityDate <= D.ProcessDate
Tried with below but it's not giving correct results.
var filteredActivity = (from e in ActiveEvents
from p in dates
where e.ActivityDate <= p.Date
select new ActiveEvent
{
ActivityDate = p.Date,
EventId = e.EventId
}).ToList();
And
var filteredActivity = (from e in ActiveEvents
from p in dates.Where(r => e.ActivityDate <= r)
select new ActiveEvent
{
ActivityDate = p.Date,
EventId = e.EventId
}).ToList();
Can you please suggest any better way to do this?
You can try this way
var filteredActivity = (from e in ActiveEvents
join p in dates
where e.ActivityDate <= p.ProcessDate
select new ActiveEvent
{
ActivityDate = p.Date,
EventId = e.EventId
}).ToList();
P/s: Ideally, between 2 tables should contain the foreign key to join like this join p in dates on e.Key equals p.ForeignKey
Based on your example, the query is filtering on ProcessDate but your linq query is filtering on p.Date. Are those the same field? The first example you gave should be correct.
I'm writing a LINQ to SQL statement, and I'm after the standard syntax for a normal inner join with an ON clause in C#.
How do you represent the following in LINQ to SQL:
select DealerContact.*
from Dealer
inner join DealerContact on Dealer.DealerID = DealerContact.DealerID
It goes something like:
from t1 in db.Table1
join t2 in db.Table2 on t1.field equals t2.field
select new { t1.field2, t2.field3}
It would be nice to have sensible names and fields for your tables for a better example. :)
Update
I think for your query this might be more appropriate:
var dealercontacts = from contact in DealerContact
join dealer in Dealer on contact.DealerId equals dealer.ID
select contact;
Since you are looking for the contacts, not the dealers.
And because I prefer the expression chain syntax, here is how you do it with that:
var dealerContracts = DealerContact.Join(Dealer,
contact => contact.DealerId,
dealer => dealer.DealerId,
(contact, dealer) => contact);
To extend the expression chain syntax answer by Clever Human:
If you wanted to do things (like filter or select) on fields from both tables being joined together -- instead on just one of those two tables -- you could create a new object in the lambda expression of the final parameter to the Join method incorporating both of those tables, for example:
var dealerInfo = DealerContact.Join(Dealer,
dc => dc.DealerId,
d => d.DealerId,
(dc, d) => new { DealerContact = dc, Dealer = d })
.Where(dc_d => dc_d.Dealer.FirstName == "Glenn"
&& dc_d.DealerContact.City == "Chicago")
.Select(dc_d => new {
dc_d.Dealer.DealerID,
dc_d.Dealer.FirstName,
dc_d.Dealer.LastName,
dc_d.DealerContact.City,
dc_d.DealerContact.State });
The interesting part is the lambda expression in line 4 of that example:
(dc, d) => new { DealerContact = dc, Dealer = d }
...where we construct a new anonymous-type object which has as properties the DealerContact and Dealer records, along with all of their fields.
We can then use fields from those records as we filter and select the results, as demonstrated by the remainder of the example, which uses dc_d as a name for the anonymous object we built which has both the DealerContact and Dealer records as its properties.
var results = from c in db.Companies
join cn in db.Countries on c.CountryID equals cn.ID
join ct in db.Cities on c.CityID equals ct.ID
join sect in db.Sectors on c.SectorID equals sect.ID
where (c.CountryID == cn.ID) && (c.CityID == ct.ID) && (c.SectorID == company.SectorID) && (company.SectorID == sect.ID)
select new { country = cn.Name, city = ct.Name, c.ID, c.Name, c.Address1, c.Address2, c.Address3, c.CountryID, c.CityID, c.Region, c.PostCode, c.Telephone, c.Website, c.SectorID, Status = (ContactStatus)c.StatusID, sector = sect.Name };
return results.ToList();
You create a foreign key, and LINQ-to-SQL creates navigation properties for you. Each Dealer will then have a collection of DealerContacts which you can select, filter, and manipulate.
from contact in dealer.DealerContacts select contact
or
context.Dealers.Select(d => d.DealerContacts)
If you're not using navigation properties, you're missing out one of the main benefits on LINQ-to-SQL - the part that maps the object graph.
Use Linq Join operator:
var q = from d in Dealer
join dc in DealerConact on d.DealerID equals dc.DealerID
select dc;
basically LINQ join operator provides no benefit for SQL. I.e. the following query
var r = from dealer in db.Dealers
from contact in db.DealerContact
where dealer.DealerID == contact.DealerID
select dealerContact;
will result in INNER JOIN in SQL
join is useful for IEnumerable<> because it is more efficient:
from contact in db.DealerContact
clause would be re-executed for every dealer
But for IQueryable<> it is not the case. Also join is less flexible.
Actually, often it is better not to join, in linq that is. When there are navigation properties a very succinct way to write your linq statement is:
from dealer in db.Dealers
from contact in dealer.DealerContacts
select new { whatever you need from dealer or contact }
It translates to a where clause:
SELECT <columns>
FROM Dealer, DealerContact
WHERE Dealer.DealerID = DealerContact.DealerID
Inner join two tables in linq C#
var result = from q1 in table1
join q2 in table2
on q1.Customer_Id equals q2.Customer_Id
select new { q1.Name, q1.Mobile, q2.Purchase, q2.Dates }
Use LINQ joins to perform Inner Join.
var employeeInfo = from emp in db.Employees
join dept in db.Departments
on emp.Eid equals dept.Eid
select new
{
emp.Ename,
dept.Dname,
emp.Elocation
};
Try this :
var data =(from t1 in dataContext.Table1 join
t2 in dataContext.Table2 on
t1.field equals t2.field
orderby t1.Id select t1).ToList();
OperationDataContext odDataContext = new OperationDataContext();
var studentInfo = from student in odDataContext.STUDENTs
join course in odDataContext.COURSEs
on student.course_id equals course.course_id
select new { student.student_name, student.student_city, course.course_name, course.course_desc };
Where student and course tables have primary key and foreign key relationship
try instead this,
var dealer = from d in Dealer
join dc in DealerContact on d.DealerID equals dc.DealerID
select d;
var Data= (from dealer in Dealer join dealercontact in DealerContact on dealer.ID equals dealercontact.DealerID
select new{
dealer.Id,
dealercontact.ContactName
}).ToList();
var data=(from t in db.your tableName(t1)
join s in db.yourothertablename(t2) on t1.fieldname equals t2.feldname
(where condtion)).tolist();
var list = (from u in db.Users join c in db.Customers on u.CustomerId equals c.CustomerId where u.Username == username
select new {u.UserId, u.CustomerId, u.ClientId, u.RoleId, u.Username, u.Email, u.Password, u.Salt, u.Hint1, u.Hint2, u.Hint3, u.Locked, u.Active,c.ProfilePic}).First();
Write table names you want, and initialize the select to get the result of fields.
from d1 in DealerContrac join d2 in DealerContrac on d1.dealearid equals d2.dealerid select new {dealercontract.*}
One Best example
Table Names : TBL_Emp and TBL_Dep
var result = from emp in TBL_Emp join dep in TBL_Dep on emp.id=dep.id
select new
{
emp.Name;
emp.Address
dep.Department_Name
}
foreach(char item in result)
{ // to do}
I have the following query:
var query = (from wo in _dbContext.WorkOrder
join opr in _dbContext.Operation
on wo.operationID equals opr.operationID
where wo.orderid == selectedorderid
select new {wo.orderid, wo.workOrderID, wo.itemID, wo.operationID, opr.operationName, wo.operationCode}).ToList();
I also have another table,which joins with workorder table,and returns multiple values.
What I want to do is,I want to join the table and get a single column of it as a concentrated column in my query such as (id1,id2,id3) etc. How can I achieve this?
What about:
var query = (from wo in _dbContext.WorkOrder
join opr in _dbContext.Operation
on wo.operationID equals opr.operationID
where wo.orderid == selectedorderid
select new {wo.orderid, wo.workOrderID, wo.itemID, wo.operationID, opr.operationName, wo.operationCode}).ToList();
var orders = queryGroupBy(i => i.workOrderID)
.Select(i => new {WorkOrderId = i.workOrderID, ConcatinatedIds = String.Join(", ", i.Select(j => j.operationID))})
.ToList();
Using Entity Framework Version=6.0.0.0 to get to get common id and orderid as shown below.
var dt1 = from p in dt.AsEnumerable()
select new
{
Id = p.Field<int>("Id"),
OrderId = p.Field<int>("OrderId")
};
var dt2 = (from order in db.Orders
select new
{
order.Id,
order.OrderId
}).ToList();
var intersect = dt1.Intersect(dt2);
Based on the list of values in intersect. I need to select all the values from Orders Table.
Trying to used code getting error "unable to create a constant value of type anonymous type only primitive types"
var result= (from a in sync.Orders
where intersect.Any(b => a.Id == b.Id && a.OrderId == b.OrderId)
select a).ToList();
You are trying to "join" an EF query with an in-memory data set, which does not work because there's not a way to embed the list and the lookup in SQL. One option is to pull the entire table into memory with AsEnumerable:
var result= (from a in sync.Orders.AsEnumberable
where intersect.Any(b => a.Id == b.Id && a.OrderId == b.OrderId)
select a).ToList();
Another option is to concatenate the Id and OrderId into one value and use Contains since that can be translated to an IN clause in SQL:
var lookup = intersect.Select(i => i.Id + "-" + i.OrderId).ToList();
var result= (from a in sync.Orders
where lookup.Contains(a.Id + "-" + a.OrderId)
select a).ToList();
I'm trying to join two tables using their common id which is MOTHERID. But he code below was working fine but at some point it starts throwing "Invalid cast exception" at:
var firstQuery = (from s in _maternalvisitvaluedb.Value select s).ToList();
I think the exception is being caused by the toList() conversion because when I remove .ToList() it works fine but I need to use that for the rest of the code to work properly. Here is some part of the code:
MaternalVisitData _maternalvisitvaluedb =
new MaternalVisitData(MaternalVisitData.strConnectionString);
MaternalCareData _maternalcarevaluedb =
new MaternalCareData(MaternalCareData.strConnectionString);
var firstQuery = (from s in _maternalvisitvaluedb.Value select s).ToList();
var secondQuery = (from t in _maternalcarevaluedb.Value select t).ToList();
var result = (from s in firstQuery
join k in secondQuery
on s.MotherId equals k.MotherId
where (DateTime)s.SecondVisit.Date == DateTime.Now.Date
select s).ToList();
Thanks for your help!
try specific type alternate of var in below lines :
var firstQuery = (from s in _maternalvisitvaluedb.Value select s).ToList();
var secondQuery = (from t in _maternalcarevaluedb.Value select t).ToList();
like this :
List<maternalvisitvaluedb> firstQuery = (list<maternalvisitvaluedb>)(from s in _maternalvisitvaluedb.Value select s).ToList();
List<maternalcarevaluedb> secondQuery = (List<maternalcarevaluedb>)(from t in _maternalcarevaluedb.Value select t).ToList();
it's a pseudo , I hope it helps you