Develop Reference

Join Table Group By Summary On Linq

Hi I try to convert the SQL query to LINQ.
SELECT C.ID, SUM(S.AMOUNT*CS.PRICE) AS TOTALCATEGORYSUMMARY
FROM CATEGORY C
INNER JOIN PRODUCT P ON P.CATEGORYID=C.ID
INNER JOIN PSTOCK S ON S.PRODUCTID=P.ID
INNER JOIN PCOST CS ON CS.PRODUCTID=P.ID
GROUP BY C.ID
I try as below:
var qry = from c in categories
join p in products on c.Id equals p.CategoryId
join s in stoks on p.Id equals s.ProductId
join t in costs on p.Id equals t.ProductId
group new {c} by new { c.Name,s.Stock,t.Amount } into ct
select (new { ct.Key.Name, AllCost=ct.Key.Amount * ct.Key.Stock });
How can I do this?

From your SQL query, your LINQ statement should be:
var qry = from c in categories
join p in products on c.Id equals p.CategoryId
join s in stoks on p.Id equals s.ProductId
join t in costs on p.Id equals t.ProductId
group new { c.Id, s.Amount, t.Price } by c.Id into ct
select new { Id = ct.Key.Id, AllCost = ct.Sum(x => x.Amount * x.Price) };
References
Group by single property
Enumerable.Sum method

Selecting max in linq query or rewriting to method chain syntax

I managed to turn this SQL query:
SELECT c.carId, c.Codename, count(c.CarId) as [CarCount],
FROM [DbEfTesting].[dbo].[Cars] c
left join Accessories a on c.CarId = a.CarId
left join CarsPeople cp on cp.CarId = c.CarId
left join People p on cp.PersonId = p.PersonId
group by c.CarId, c.Codename
into a LINQ query:
var x = from c in _context.Cars
join a in _context.Accessories on c.CarId equals a.Car.CarId
join j in _context.CarsPeople on c.CarId equals j.CarId
join p in _context.People on j.PersonId equals p.PersonId
group c by new { c.CarId, c.Codename } into g
select new VMCarAggregate()
{
CarId = g.Key.CarId,
Codename = g.Key.Codename,
CarCount = g.Count()
};
But now I'm lost trying to include a max value e.g the SQL:
SELECT c.carId, c.Codename, count(c.CarId) as [CarCount], max(a.AccessoryId) ...
I googled it and found lots of answers for method syntax. If I were using method chain syntax, I know I could do something like this:
_context.Accessories.Max(a => a.AccessoryId);
but I can't figure out how to do the group by in method chain syntax so either:
How can I convert that query to method syntax?
or
How can I inject a select on the max a.AccessoryId in the LINQ query format?

Try the below code once:
var x = from c in _context.Cars
join a in _context.Accessories equals a.Car.CarId
join j in _context.CarsPeople on c.CarId equals j.CarId
join p in _context.People on j.PersonId equals p.PersonId
group new { c.CarId, c.Codename, a.AccesoryId } by new { c.CarId, c.Codename } into g
select new
{
CarId = g.Key.CarId,
Codename = g.Key.Codename,
CarCount = g.Count(),
MaxAccesory = g.Max(z => z.AccesoryId)
};

WHERE condition with SELECT, MAX statement using LINQ/Lambda

I am trying to convert below SQL query to LINQ/Lambda in C#
SELECT DISTINCT M.InternalID, P.Code
FROM (
dbo.MeasureValue MV
INNER JOIN dbo.Measure M ON MV.MeasureID = M.ID
INNER JOIN dbo.Provider P ON MV.ProviderID = P.ID
)
WHERE MV.ReportingDate = (
SELECT MAX(ReportingDate)
FROM (
SELECT ReportingDate
FROM dbo.MeasureValue
WHERE MeasureID = MV.MeasureID
) MaxReportingDate
);
I have got so far,
(from MV in MeasureValues
join M in Measures on MV.MeasureID equals M.ID
join P in Providers on MV.ProviderID equals P.ID
Where //???
select new //Distinct??
{ M.InternalID, P.Code} )
Could someone please guide me how to use nested WHERE condition as in SQL query and do MAX of nested SELECT and DISTINCT on whole?
As a whole the LINQ/Lamda should output same result as SQL query.
*I am new to SQL and LINQ
Thanks in advance.

Try this one:
var query =
from mv in MeasureValues
join m in Measures on mv.MeasureID equals m.ID
join p in Providers on mv.ProviderID equals p.ID
where mv.ReportingDate ==
(from mv2 in MeasureValues
where mv2.MeasureID == mv.MeasureID
orderby mv2.ReportingDate descending
select mv2.ReportingDate
).FirstOrDefault()
select new { m.InternalID, p.Code };
var distinct =
from q in query
group q by new { q.InternalID, q.Code} into gr
select new
{
InternalID = gr.First().InternalID,
Code = gr.First().Code
};
var result = distinct.ToList();
Another option to find max ReportingDate:
var query =
from mv in MeasureValues
join m in Measures on mv.MeasureID equals m.ID
join p in Providers on mv.ProviderID equals p.ID
where mv.ReportingDate == MeasureValues.Where(x => x.MeasureID == mv.MeasureID).Select(x => x.ReportingDate).Max()
select new { m.InternalID, p.Code };

Add additional fields to Linq group by

I have the LINQ to SQL as below, which works fine.
var qry = (from h in dc.Timesheets
join s in dc.Users on h.UserID equals s.UserID
join ug in dc.UserGroups on s.UserGroupID equals ug.UserGroupID
where h.BookedOn >= _dateFrom.Value && h.BookedOn <= _dateTo.Value
group h by ug.UserGroupID into g
orderby g.Count() descending
select new
{
UserGroupingID = g.Key,
BookingsPerDay = g.Count() / days
}).ToList();
Now I want to add the name of the User Group, but somehow I struggle to get the LINQ right.
My limited knowledge tells me I should add the Description to the Group clause as follow, but it's a no-go:
I try:
var qry = (from h in dc.Timesheets
join s in dc.Users on h.UserID equals s.UserID
join ug in dc.UserGroups on s.UserGroupID equals ug.UserGroupID
where h.BookedOn >= _dateFrom.Value && h.BookedOn <= _dateTo.Value
group h, GroupDescription = ug.Description by ug.UserGroupID into g
orderby g.Count() descending
select new
{
UserGroupingID = g.Key,
Description = g.Key.GroupDescription
BookingsPerDay = g.Count() / days
}).ToList();
Error: Cannot convert lambda expression to type
'System.Collections.Generic.IEqualityComparer' because it is not
a delegate type

I think you might missing the new keyword here!!
var qry = (from h in dc.Timesheets
join s in dc.Users on h.UserID equals s.UserID
join ug in dc.UserGroups on s.UserGroupID equals ug.UserGroupID
where h.BookedOn >= _dateFrom.Value && h.BookedOn <= _dateTo.Value
group new {h, GroupDescription = ug.Description} by new {GroupDescription} into g
orderby g.Count() descending
select new
{
UserGroupingID = g.Key,
Description = g.Key.GroupDescription
BookingsPerDay = g.Count() / days
}).ToList();

Shouldn't it be an == for the GroupDescription? And aren't you missing a comma in the select new statement?

Wrting a SQL query in LINQ

I have this so far:
var query = (from g in this.Context.Groups
where g.ID == groupID &&
g.TaxId == groupTaxId
select g.Group_K);
Then the SQL query I want to add is this:
select zipCode from ADDRESSES where ADDRESS_K in
(select ADDRESS_K from GROUPADDRESS
where GROUP_K = "is in Group_K found above "
and address_type = "address type variable I pass into this method"
and ACTIVE = 1)
I can't figure it out how to add a new LINQ query or update the one I have to account for the new SQL I am trying to add. Thanks for help.

How about this one?
var group_key = (from g in this.Context.Groups
where g.ID == groupID
&& g.TaxId == groupTaxId
select g.Group_K);
var query = (from a in this.Context.Addresses
join ga in this.Context.GroupAddress on a.Address_K equals ga.Address_K
where (group_key.Contains(ga.Group_K) && a.ZipCode == "whatever passed from method" && ga.Address_Type == "whatever passed from your method")
select a);

IN statement is equivalent to Contains method call in LINQ to Entities:
var query = from a in this.Context.Addresses
where (from g in this.Context.Groups
where g.ID == groupID && g.TaxId == groupTaxId
select g.Group_K).Contains(a.Address_K);
select a.ZipCode;
You could also rewrite your query to use JOIN instead of nested queries:
var query = from a in this.Context.Addresses
join g in this.Context.Groups on a.Address_K equals g.Group_K
where g.ID == groupID && g.TaxId == groupTaxId
select a.ZipCode;