I have this simple sql query:
select c.LastName, Sum(b.Debit)- Sum(b.Credit) as OpenBalance from Balance as b
inner join Job as j on (b.Job = j.ID)
inner join Client as c on (j.Client = c.ID)
Group By c.LastName
and I am trying to convert it to work in linq like this:
from b in Balance
join j in Job on b.Job equals j.ID
join c in Client on j.Client equals c.ID
group b by new { c.LastName } into g
select new {
Name = c.Lastname,
OpenBalance = g.Sum(t1 => t1.Credit)
}
but when I try to run it in LINQPad I get the following message:
The name 'c' does not exist in the
current context
and it highlights c.Lastname in select new statement.
Any help on this will be greatly appreciated.
Thank you.
Well, you've grouped b by c.LastName. So after the grouping operation, you're dealing with g which is a grouping with the element type being the type of b, and the key type being the type of c.LastName. It could well be that all you need is:
select new {
Name = g.Key,
OpenBalance = g.Sum(t1 => t1.Credit)
}
... but if you need to get at any other aspects of c, you'll need to change your grouping expression.
Related
SELECT ra.ResidentID, ra.RoomID, r.Number, ra.StartDate, p.FacilityID
FROM(
SELECT ResidentID, MAX(StartDate) AS max_start
FROM RoomAssignments
GROUP BY ResidentID
) m
INNER JOIN RoomAssignments ra
ON ra.ResidentID = m.ResidentID
AND ra.StartDate = m.max_start
INNER JOIN Rooms r
ON r.ID = ra.RoomID
INNER JOIN Person p
ON p.ID = ra.ResidentID
inner join ComplianceStage cs
ON cs.Id = p.ComplianceStageID
ORDER BY ra.EndDate DESC
I'm trying to figure out how to convert this to C# using LINQ. I'm brand new with C# and LINQ and can't get my subquery to fire correctly. Any chance one of you wizards can turn the lights on for me?
Update-----------------
I think I've got the jist of it, but am having trouble querying for the max startdate:
var maxQuery =
from mra in RoomAssignments
group mra by mra.ResidentID
select new { mra.ResidentID, mra.StartDate.Max() };
from ra in RoomAssignments
join r in Rooms on ra.RoomID equals r.ID
join p in Persons on ra.ResidentID equals p.ID
where ra.ResidentID == maxQuery.ResidentID
where ra.StartDate == maxQuery.StartDate
orderby ra.ResidentID, ra.StartDate descending
select new {ra.ResidentID, ra.RoomID, r.Number, ra.StartDate, p.FacilityID}
Following my LINQ to SQL Recipe, the conversion is pretty straight forward if you just follow the SQL. The only tricky part is joining the range variable from the subquery for max start date to a new anonymous object from RoomAssignments that matches the field names.
var maxQuery = from mra in RoomAssignments
group mra by mra.ResidentID into mrag
select new { ResidentID = mrag.Key, MaxStart = mrag.Max(mra => mra.StartDate) };
var ans = from m in maxQuery
join ra in RoomAssignments on m equals new { ra.ResidentID, MaxStart = ra.StartDate }
join r in Rooms on ra.RoomID equals r.ID
join p in Persons on ra.ResidentID equals p.ID
join cs in ComplianceStage on p.ComplianceStageID equals cs.Id
orderby ra.EndDate descending
select new {
ra.ResidentID,
ra.RoomID,
r.Number,
ra.StartDate,
p.FacilityID
};
i plan to join 2 table, and get the distinct value of language column. How should i achieve that in Linq? I try add 'group' but no luck. Besides, i want to select s value too together with r distinct language value.
My code:
public ActionResult QuestionLink(int Survey_ID)
{
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model
on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
group r.language << this is not work **
select r;
return PartialView(query.ToList());
}
This is what in MoreLinq is called DistinctBy. But if that method works on IEnumerable, so you can't use it in an EF query. But you can use the same approach:
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
group new { r, s } by r.language into grp
select grp.FirstOrDefault();
But I wonder if this really is what you want. The result depends on the ordering of languages that the database happens to return. I think you should add a predicate for a specific language and remove the grouping:
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model
on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
&& r.language == someVariable
select new { r, s };
You can do like this:
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model
on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
group new {r, s} by r.language into rg
select rg.Key;
I want to make this query in linq to sql .
Please help. I am new to linq and having problem to with the group by clause .
Here is the sql query
select count(USERID), d.DEPTNAME from USERS u
join department d on u.DEPTID = d.DEPTID
group by u.DEPTID, d.DEPTNAME
A more direct translation would be like this:
var query =
from u in db.Users
join d in db.Departments on u.DeptId equals d.DeptId
group d by new { d.DeptId, d.DeptName } into g
select new
{
g.Key.DeptName,
Count = g.Count(),
};
Though I think it would be better off written like this:
// looks like we're counting users in each department
var query =
from d in db.Departments
select new
{
d.DeptName,
Count = db.Users.Count(u => u.DeptId == d.DeptId),
};
I need to write Join statment after writing query in linq
example :
var Query = (from Tab in Db.Employees
select Tab)
as i have some cases to perform join operation so
i need to do it on this Query Query.Join(Join with another Table like Department); I need the Syntax
if (DeptID != -1){ Query.Join(Join with table Department where FkDeptID = DeptID); }
Consider the usage of join in the LINQ 'query syntax':
from t1 in db.Table1
join t2 in db.Table2 on t1.field equals t2.field
select new { t1.field2, t2.field3}
Something like this?
var results = (from q in Query
join m in myList on q.SomeID = m.SomeID
select unknown);
Try using this query:
var Query =
from e in Db.Employees
join d in Db.Departments on e.FkDeptID equals d.DeptID into departments
select new
{
Employee = e,
Department = departments.SingleOrDefault(),
};
This works assuming that when e.FkDeptID == -1 that there is no record in the Departments table and in that case Department would be assigned null.
You should never have more than one department for an employee so I've used SingleOrDefault rather than FirstOrDefault.
This is the SQL I want (ClearinghouseKey is a bigint):
select *
from ConsOutput O
where O.ClearinghouseKey IN (
select distinct P.clearinghouseKey
from Project P
Inner join LandUseInProject L on L.ClearinghouseKey = P.ClearinghouseKey
where P.ProjectLocationKey IN ('L101', 'L102', 'L103')
and L.LandUseKey IN ('U000', 'U001', 'U002', 'U003')
)
The inner query is straight forward and gives correct results in LINQPad:
var innerQuery = (from p in Projects
join l in LandUseInProjects on p.ClearinghouseKey equals l.ClearinghouseKey
where locations.Contains(p.ProjectLocationKey)
&& (landuses.Contains(l.LandUseKey))
select new { p.ClearinghouseKey }).Distinct();
But the outer query gives the error: Type arguments from ...Contains..cannot be inferred from usage:
var returnQuery = from o in OperOutput
where (innerQuery).Contains(o.ClearinghouseKey)
select o;
Is it because ClearinghouseKey is a bigint? Any other ways to write this query?
Thanks,
Jeanne
Don't use an anonymous type:
select new { p.ClearinghouseKey })
Should be
select p.ClearinghouseKey)
Also consider using Any instead of Contains (I don't have reasons for choosing one over the other, yet).
where innerQuery.Any(i => i == o.ClearinghouseKey)