What is the syntax for an inner join in LINQ to SQ

Question

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

Answer 1

Use Linq Join operator:

var q =  from d in Dealer
         join dc in DealerConact on d.DealerID equals dc.DealerID
         select dc;

Answer 2

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.

Answer 3

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 }

Answer 4

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
                   };

Answer 5

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(); 

Answer 6

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.