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How to make this query with lambda expression in Entity Framework?

This is my SQL query:
select
m.Name, s.Time, t.TheaterNumber
from
Movies m
join
MovieSeanceTheaters mst on mst.MovieId = m.MovieID
join
Theaters t on t.ID = mst.TheaterId
join
Seances s on mst.SeanceId = s.ID
This is my attempt at a Linq query:
var result = (from m in _context.Movies
join mst in _context.MovieSeanceTheaters on m.ID equals mst.MovieId
join t in _context.Theaters on mst.TheaterId equals t.ID
join s in _context.Seances on mst.TheaterId equals s.ID
select new { Film = m.Name, Salon = t.Name, Seans = s.Time }
).ToList();
I made this attempt, but I want to make with lambda for instance:
var result = movieManager.GetAll().Where(x => x.MovieSeanceTheaters)....
I couldn't do that.

If I understand you correctly, you want to rewrite your query from query syntax to method syntax?
Here we are!
var result = _context.Movies
.Join(_context.MovieSeanceTheaters,
m => m.MovieID,
mst => mst.MovieID,
(m, mst) => new
{
m = m,
mst = mst
})
.Join(_context.Theaters,
temp0 => temp0.mst.TheaterID,
t => t.ID,
(temp0, t) =>
new
{
temp0 = temp0,
t = t
})
.Join(_context.Seances,
temp1 => temp1.temp0.mst.TheaterID,
s => s.ID,
(temp1, s) =>
new
{
Film = temp1.temp0.m.Name,
Salon = temp1.t.TheaterNumber,
Seans = s.Time
});
Looks ugly, doesn't it?
Most often, the method syntax is more compact and convenient. But in this case, leave it as is.

SQL query to LINQ conversion with nested select statements

I want to convert the following query to LINQ:
SELECT LV.* FROM LowerVehicles LV
INNER JOIN (Select VSerial,MAX(updatedOn) MaxUpdatedOn from LowerVehicles group by vserial) LVG
ON LV.VSerial = LVG.VSerial AND LV.updatedOn = LVG.MaxUpdatedOn

Not knowing your entities classes, here is an approximation. You can use query syntax or fluent syntax. Sometimes one is preferable over the other, and in the case of joins and grouping I prefer to use query syntax.
QUERY SYNTAX
var query = from LV in LowerVehicles
join LVG in (
from r in LowerVehicles
group r by r.vserial into g
select new {VSerial = g.Key, MaxUpdatedOn = g.Max(t => t.updatedOn)})
on LV.VSerial equals LVG.Vserial
and LV.updatedOn equals LVG.MaxUpdatedOn
select LV;
FLUENT SYNTAX
var lvg = LowerVehicles.GroupBy(t => t.vserial)
.Select(g => new {
VSerial = g.Key,
MaxUpdatedOn = g.Max(t => t.updatedOn)
});
var query = LowerVehicles.Join(
lvg,
a => new { a.VSerial, a.updatedOn },
b => new { b.VSerial, b.MaxUpdatedOn },
(a, b) => new { LV = a, LVG = b}
)
.Select(t=> t.LV);

Something like this?
Something.LowerVehicles
.Join(something.LowerVehicles.Select(y => new { y.VSerial, updatedOn = y.updatedOn.Max() }).GroupBy(z => z.VSerial),
x => new { x.VSerial, x.updatedOn },
lvg => new { lvg.VSerial, lvg.updatedOn },
(x, y) => x)

How to write lambda expression for an sql expression?

I have an SQL expression
select S.SpecialtyName, COUNT(distinct SUC.SiteUserId) as Subscribers
from SiteUserContent SUC Inner join
Specialties S on SUC.SpecialtyId = S.SpecialtyId Inner join
SiteUser SU on SUC.SiteUserId = SU.SiteUserId
where SU.DeletedFlag = 0
group by S.SpecialtyName
Order by S.SpecialtyName
What will be the corresponding LINQ expression for the same?

from suc in context.SiteUserContent
join s in context.Specialties on suc.SpecialtyId equals s.SpecialtyId
join su in context.SiteUser on suc.SiteUserId equals su.SiteUserId
where su.DeletedFlag == 0
select new { suc.SiteUserId, s.SpecialityName } into x
group x by x.SpecialityName into g
orderby g.Key
select new {
SpecialityName = g.Key,
Subscribers = g.Select(i => i.SiteUserId).Distinct().Count()
}
Generated SQL will not be same, but I think result of query execution should be same.

var results = contex.SiteUserContent
.Join(context.Specialties, suc => suc.SpecialtyId, s => s.SpecialtyId, (suc, s) => new { suc, s })
.Join(context.SiteUser, i = i.suc.SiteUserId, su => su.SiteUserId, (i, su) => new { suc = i.suc, s = i.s, su = su })
.Where(i => i.su.DeletedFlag == 0)
.GroupBy(i => i.s.SpecialtyName)
.Select(g => new {
SpecialityName = g.Key,
Subscribers = g.Select(i => i.suc.SiteUserId)
.Distinct()
.Count()
})
.OrderBy(i => i.SpecialityName);

Linq to SQL with GroupBy and Detail - Is there a better way to do this?

I have some SQL and am trying to make the equivalent in LINQ. This is the SQL:
SELECT Categories.CategoryDescription, Categories.CategoryType AS Type,
Categories.Category, COUNT(CategoryLinks.OrgID) AS CountOfOrgs
FROM CategoryLinks
INNER JOIN Categories ON Categories.CategoryID = CategoryLinks.CategoryID
GROUP BY Categories.Category, Categories.CategoryType, Categories.CategoryDescription
ORDER BY CategoryDescription ASC
Essentially, I want a list of everything from the Categories table and a count of the number of OrgId's in the CategoryLinks table that links to it.
Below is the query I am performing at the moment. There has to be a more efficient way to do this. Am I wrong?
var cnts = (from c in db.Categories
join cl in db.CategoryLinks on c.CategoryID equals cl.CategoryID
group new { c, cl } by new
{
c.CategoryID
} into g
select new
{
CategoryID = g.Key.CategoryID,
categoryCount = g.Count()
});
var results = (from c in db.Categories
join cn in cnts on c.CategoryID equals cn.CategoryID
select new
{
c.CategoryID,
c.CategoryDescription,
c.CategoryType,
Category = c.Category1,
cn.categoryCount
});

I think you want to use the GroupJoin method:
Categories.GroupJoin(
CategoryLinks,
x => x.CategoryID,
y => y.CategoryID,
(x,y) => new{
x.CategoryID,
x.CategoryDescription,
x.CategoryType,
Category = x.Category1,
CategoryCount = y.Count() })
In query syntax, this is written as join..into:
from c in db.Categories
join cl in db.CategoryLinks on c.CategoryID equals cl.CategoryID into catGroup
select new
{
c.CategoryID,
c.CategoryDescription,
c.CategoryType,
Category = c.Category1,
CategoryCount = catGroup.Count()
}

Try this:
var bbb = categories.Join(categoryLinks, c => c.CategoryID, cl => cl.CategoryId, (c, cl) => new {c, cl})
.GroupBy(g => g.c)
.Select(g => new {count = g.Count(), Category = g.Key});
It returns count and all data that is in Category. We group by all columns in category and place result in new anonymous type variable that contains 2 properties: Count, that contains count and Category that is of type Category and contains all data that is in category row.
If you want, you can rewrite it as:
var bbb = categories.Join(categoryLinks, c => c.CategoryID, cl => cl.CategoryId, (c, cl) => new {c, cl})
.GroupBy(g => g.c)
.Select(g => new
{
CategoryID = g.Key.CategoryId,
CategoryDescription = g.Key.CategoryDescription,
CategoryType = g.Key.CategoryType,
Category = g.Key.Category1,
categoryCount = g.Count()
});

what am i doing wrong in constructing Linq query

I am trying to write equivalent linq code for following query.
SELECT A.*
FROM
(
SELECT * FROM TableA
WHERE id = 100
) a
JOIN
(
SELECT Name, MAX(AnotherId) AnotherId
FROM TableA
WHERE id = 100
GROUP BY Name
) b
on a.Name = b.Name and a.AnotherId = b.AnotherId
This is the linq
var Collection = from R in DbContext.TableA
join G in (DbContext.TableA.Where(r => r.Id == 100).GroupBy(r => new { r.Name, r.AnotherId } ).Select(g => new { Name = g.Name , AnotherId = g.Max(o => o.AnotherId) }))
on new { R.Name, R.AnotherId } equals new { G.Name, G.AnotherId }
where R.Id == 100
select R;
But I am getting following compilation error that I don’t know how to fix. Any thoughts
The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'Join'.
Error 7 'System.Linq.IGrouping' does not contain a definition for 'Name' and no extension method 'Name' accepting a first argument of type 'System.Linq.IGrouping' could be found (are you missing a using directive or an assembly reference?)

You group by r.Name, r.AnotherId, when you just want to group by r.Name.
var Collection = from R in DbContext.TableA
join G in (DbContext.TableA
.Where(r => r.Id == 100)
.GroupBy(r => r.Name)
.Select(g => new { Name = g.Key , AnotherId = g.Max(o => o.AnotherId) }))
on new { R.Name, R.AnotherId } equals new { G.Name, G.AnotherId }
where R.Id == 100
select R;
And to have all in Fluent Syntax
var collection = DbContext.TableA
.Where(t1 => t1.Id == 100)
.Join(DbContext.TableA
.Where(t2 => t2.Id == 100)
.GroupBy(t2 => t2.Name)
.Select(group => new{Name = group.Key,
AnotherId = group.Max(e => e.AnotherId)})
),
t1 => new{t1.Name, t1.AnotherId} ,
t2 => new{t2.Name, t2.AnotherId},
(t1, t2) => t1);

llHi you need the following syntax, notice the addition of 'Key'
var Collection = from R in DbContext.TableA
join G in (DbContext.TableA.Where(r => r.Id == 100)
.GroupBy(r => new { r.Name, r.AnotherId } )
.Select(g => new { Name = g.Key.Name , AnotherId = g.Max(o => o.AnotherId) }))
on new { R.Name, R.AnotherId } equals new { G.Name, G.AnotherId }
where R.Id == 100
select R;

I would recommend using the query syntax for all parts of your query. By doing it this way, your linq query will have a more similar structure to your original sql query. It would look like this:
var query =
from a in
(from x in DbContext.TableA
where x.ID == 100
select x)
join b in
(from x in DbContext.TableA
where x.ID == 100
group x by x.Name into x
select new
{
Name = x.Key,
AnotherId = x.Max(o => o.AnotherId),
})
on new { a.Name, a.AnotherId } equals new { b.Name, b.AnotherId }
select a;

saj and Raphael both have found good points:
.GroupBy(r => new { r.Name, r.AnotherId } )
.Select(g => new { Name = g.Name , AnotherId = g.Max(o => o.AnotherId) }))
Groups don't have a Name. Each group has a Key (and the Key has a Name and AnotherId).
Since you want the Max(AnotherId), you don't want to include AnotherId in your grouping Key (same as it is not present in the GroupBy clause of the original query).
.GroupBy(r => r.Name) //the Name is the Key
.Select(g => new { Name = g.Key, AnotherId = g.Max(o => o.AnotherId) }))