So I have a SQL view that I've created that provides me what I need. Essentially it's a job position billeting system that shows how many positions have been authorized vs filled (or assigned).
SELECT Companies.Name AS Company, Grades.Name AS Grade, Series.Name
AS Series, Positions.Authorized, COUNT(People.PersonId) AS Assigned
FROM Companies INNER JOIN
Positions ON Companies.Id = Positions.CompanyId INNER JOIN
Series ON Positions.SeriesId = Series.Id INNER JOIN
Grades ON Positions.GradeId = Grades.Id INNER JOIN
People ON Positions.CompanyId = People.CompanyId AND
Positions.SeriesId = People.SeriesId AND Positions.GradeId = People.GradeId
GROUP BY Companies.Name, Grades.Name, Series.Name, Positions.Authorized
Now what I'd like to be able to do is recreate this in a LINQ query. I've almost got it where I need it; however, I can't figure out how to add the counted column at the end that's based on the People table.
Here's my current LINQ query:
var query = from a in db.Companies
join b in db.Positions on a.Id equals b.CompanyId
join c in db.Series on b.SeriesId equals c.Id
join d in db.Grades on b.GradeId equals d.Id
join e in db.People on new { b.CompanyId, b.SeriesId, b.GradeId } equals new { e.CompanyId, e.SeriesId, e.GradeId }
group a by new { CompanyName = a.Name, GradeName = d.Name, SeriesName = c.Name, b.Authorized, e.PersonId } into f
select new { Company = f.Key.CompanyName, Grade = f.Key.GradeName, Series = f.Key.SeriesName, f.Key.Authorized, Assigned = /* needs to be Count(People.PersonId) based on last join */ )};
Thanks in advance for any help you can provide!
Figured it out. The reason why it was posting multiple rows and not doing a proper count on the same row was because in my "group by" I added in "e.PersonId" when it should have simply been removed. I also had to add a few things to make it work on the front-end razor views since it's an anonymous type (this doesn't have anything to do with the original question, but thought I'd give reason to the changes). So the person who removed their answer, you were partially right, but the reason it wasn't working was because of the additional fieldin the group by:
dynamic query = (from a in db.Companies
join b in db.Positions on a.Id equals b.CompanyId
join c in db.Series on b.SeriesId equals c.Id
join d in db.Grades on b.GradeId equals d.Id
join e in db.People on new { b.CompanyId, b.SeriesId, b.GradeId } equals new { e.CompanyId, e.SeriesId, e.GradeId }
group a by new { CompanyName = a.Name, GradeName = d.Name, SeriesName = c.Name, b.Authorized } into f
select new { Company = f.Key.CompanyName, Grade = f.Key.GradeName, Series = f.Key.SeriesName, Authorized = f.Key.Authorized, Assigned = f.Count()}).AsEnumerable().Select(r => r.ToExpando());
And what it looks like on the page:
I want to write a linq query which retrieves the data in the following format.
Assume that there are two tables - Department and Employee
Department
Dept_id| Manager_id
Employee
Emp_id| Dept_id| Emp_data
The relationship between Department and Employee table is one to many. The Department table also stores the manager employee id in that particular department. So Manager_id is nothing but the employee_id.
Now I want to get the data as follows
Dept_id, Manager_id, Emp_data(data of Manager_id), Count(employees in that department)
If I do the join on two tables i can get data of Manager but unable to get the count of all employees in that department. Any help would be appreciated.
You could do something like this:
var result=
(
from dep in db.Department
join emp in db.Employee
on dep.Manager_id equals emp.Emp_id
select new
{
dep.Dept_id,
emp,
NumberOfEmp= db.Employee.Count(c=>c.Dept_id==dep.Dept_id)
}
).ToList();
Where db is the linq data context
You could do a group join. If you have a preferred handcoded SQL statement that you would like to be generated from your LINQ query. You may want to experiment a bit with different formats to see which one allows you to generate the "best" SQL.
var result = from d in context.Departments
join e in context.Employees on d.dept_id equals e.dept_id into g
select new {
dept_id = d.dept_id,
manager_id = d.manager_id,
manager_data = g.Single(x => x.emp_id == d.manager_id).emp_data,
employee_count = g.Count()
};
or
var result = from d in context.Departments
join e in context.Employees on d.dept_id equals e.dept_id into g
from m in g where m.emp_id == d.manager_id
select new {
dept_id = d.dept_id,
manager_id = d.manager_id,
manager_data = m.emp_data,
employee_count = g.Count()
};
I want to include a table in some conditions in Linq.
I am looking for sth like this:
var query = from x in context.Messages
if(x.senderID != 0)
{
join et in context.ETs on x.senderID equals et.ID
}
where x.Getter == SSN
select new { x.id, x.message}
Is this kind of approach possible or do I have to write two different linq queries and then I will combine them?
var query = from a in context.Messages
join b in context.ETs
on a.senderID equals b.ID
into temp
from b in temp.DefaultIfEmpty()
where a.Getter == SSN
select new { a.id, a.message}
Query below yields no results:
var query = from g in context.Groups
join sl in context.GroupDancerLinks on g.Id equals sl.GroupId into sls
join usl in context.GroupForeignDancerLinks on g.Id equals usl.GroupId into usls
from sl in sls.DefaultIfEmpty()
from usl in usls.DefaultIfEmpty()
where usl.IsLead
where sl.IsLead
select new GroupGridDTO
{
Id = g.Id,
LeadName = sl.Dancer.Name,
UnregisteredLeadName = usl.ForeignDancer.Name,
DancersCount = sls.Count(),
ForeignDancersCount = usls.Count()
};
However, when same query is modified to use FirstOrDefault, results are found:
var query = from g in context.Groups
join sl in context.GroupDancerLinks on g.Id equals sl.GroupId into sls
join usl in context.GroupForeignDancerLinks on g.Id equals usl.GroupId into usls
select new GroupGridDTO
{
Id = g.Id,
LeadName = sls.Where(sl => sl.IsLead).Select(sl => sl.Dancer.Name).FirstOrDefault(),
UnregisteredLeadName = usls.Where(usl => usl.IsLead).Select(usl => usl.ForeignDancer.Name).FirstOrDefault(),
DancersCount = sls.Count(),
ForeignDancersCount = usls.Count()
};
Looking on how queries are written, results should be the same. What is wrong with first query?
EDIT:
Tables "Groups" and "ForeignDancers" are related with M2M table "GroupForeignDancerLinks".
Tables "Groups" and "Dancers" are related with M2M table "GroupDancerLinks".
In the first query if a given row has IsLead as being false the row will be removed entirely. In the second query the row exists, you just leave the corresponding item's name blank.
The queries are also semantically different if there are multiple matches for a given row in the left table. The first will list all matching rows, the latter only the first.
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}