I am trying to join three SQL tables in LINQ c# for the below SQL
SELECT
rpp.*
FROM dbo.Orgs ao
LEFT JOIN dbo.Afflia rpa
ON rpa.AccountId = ao.ID
INNER JOIN dbo.reports rpp
ON rpp.Id = rpa.reporttId
WHERE ao.Name like '%xyz%'
above query returns data but the equivalent LINQ query doesn't as in below
from a in context.Orgs
join aff in context.Afflia on a.ID equals aff.AccountId
join prescriber in context.Reports on aff.reportId equals prescriber.Id
where a.ORG_NAME.Contains("xyz")
May I know where the mistake is?
In LINQ you did INNER join but In SQL, you did LEFT join.
Try this instead:
from a in context.Orgs
join aff in context.Afflia on a.ID equals aff.AccountId into affs
from aff in affs.DefaultIfEmpty()
join prescriber in context.Reports on aff.reportId equals prescriber.Id
where a.ORG_NAME.Contains("xyz")
In your SQL you are doing a LEFT join to dbo.Afflia, but in your LINQ you are doing an inner join. You need to add "DefaultIfEmpty(), eg
from aff in context.Afflia.Where(join condition here).DefaultIfEmpty()
You could do:
var prescribers = (from a in context.Orgs
from aff in context.Afflia.Where(aff => aff.AccountId == a.ID)
from prescriber in context.Reports.Where(pres => pres.Id == aff.reportId)
where a.ORG_NAME.Contains("xyz")
select prescriber)
.ToList();
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}
What is an equivalent LINQ query to the following SQL query:
Select Id, Name
From Table1 tbl1
Where Id in ( Select Id From Table2)
You basically described an inner join with selection of rows from one table:
var result = from t1 in Table1
join t2 in Table2
on t1.Id equals t2.Id
select new{t1.Id, t1.Name};
Next SQL statement will be generated using EF and MS SQL:
SELECT t1.Id, t1.Name
FROM Table1 AS t1
INNER JOIN Table2 AS t2 ON t1.Id = t2.Id
Note, that if you are selecting non-unique items from Table2, you can potentially have duplicates in the result. Use next query to avoid this problem, cons: it loads all ids from Table2 into memory, pros: more time efficient. Checkout Felipes answer's, which is also quite good, but has it's own cons discussed in the comment section.
var table2Ids = new HashSet<int>(context.Table2.Select(t2 => t2.Id));
var result = context.Table1
.Where(t => table2Ids.Contains(t.Id))
.Select(t => new{t.Id, t.Name});
try using the Contains method:
var query = from c in db.Table1
where db.Table2.Select(x => x.Id).Contains(c.Id)
select new { c.Id, c.Name };
var result = query.ToList();
I need help to convert a SQL query to entity query in my C# code.
The query combines 4 different tables together which is as follows:
SELECT a.email,
a.status,
a.createdat,
b.unitprice,
c.name,
d.name,
e.name
FROM Orders a,
Orderdetails b,
ServiceOptions c,
services d,
merchants e
WHERE a.id=b.orderid AND c.id=b.serviceoptionid
AND c.serviceid=d.id AND d.merchantid=e.id
var query = from a in context.Orders
join b in context.OrderDetails on a.id equals b.orderid
join c in context.ServiceOptions on b.serviceoptionid equals c.id
join d in context.services on c.serviceid equals d.id
join e in context.merchants on d.merchantid equals e.id
select new { a.email,
a.status,
a.createdat,
b.unitprice,
c.name,
d.name,
e.name };
I think you are going the opposite direction. Create a entity framework first and then use LINQ from the EF to create the SQL. It should be EF->LINQ-SQL. The whole idea of EF is the user doesn't have to create a sql. This query can be done in LINQ to SQL after EF is created in the project.
I have a sql query which is to be converted to Linq
Select b.title
from TableA as a
inner join TableB as b
on a.Email=b.Email
where a.Title<>b.Title
the query which i have tried is
var query =from s in TableA
join r in TableB
on r.Email equals s.Email
but not able to replicate the where clause which may include many columns
My requirement is i need to compare the 2 tables on a primary key column and then get the other column values which do not match
You need a "select" at the end of the query, and you need to get the inputs in the right order:
var query = from s in TableA
join r in TableB on s.Email equals r.Email
where s.Title != r.Title
select s.Title;
For multiple columns, use an anonymous type:
var query = from s in TableA
join r in TableB
on new { s.Email, s.Foo } equals new { r.Email, r.Foo }
where s.Title != r.Title
select s.Title;