hi I'm using the query below to select studentId and Score from table1 now i want select users that i selected their ids from table2, how i can select it with ids?
i can select users with this query from v in dc.tbl_Students select v but i want select some users that i have their id.
var qBestMan = (from T in (((from tbl_ActPoints in dc.tbl_ActPoints
select new
{
StudentId = (int?)tbl_ActPoints.StudentId,
Score = (int?)tbl_ActPoints.Score
}).Concat(
from tbl_EvaPoints in dc.tbl_EvaPoints
select new
{
StudentId = (int?)tbl_EvaPoints.StudentId,
Score = (int?)tbl_EvaPoints.Score
})))
group T by new
{
T.StudentId
} into g
orderby g.Sum(p => p.Score) descending
select new
{
g.Key.StudentId,
HighScoreUser = g.Sum(p => p.Score)
}).ToArray();
Try something like this:
//qBestMan must be a List, or a IEnumarable and not a Array. Remove the .ToArray() at the end, or substitute it by .ToList()
var Result = from users in dc.tbl_Students
join bestMen in qBestMan on bestMen.StudentId equals users.userid
select new
{
//fields that you want
example = users.example,
other = bestMen.other
};
Related
I'm trying to get all students last attended class from database. I wrote tsql code and it works very well howevery i couldn't do the same on entityframework core.
This code below works for me.
select a.student, b.class, b.attend from students a inner join class b on b.id = (
select top 1 id
from class
where student = a.student order by attend desc
)
Also this is my attemp on writing EF query.
datavalue = db.students.join(
db.class, m => m.student,
s => s.student, (m, s) => new joinedstudentswclass { class = s.class, student = m.student }
).tolist();
u should use firstOrDefault to get a single record.
if u wanna order something, you should be used orderBy methods.
.OrderBy(x => x.City) for ascending students
.OrderByDescending(x => x.City) for descending students
the code should be something like
OrderByDescending(x=>x.Students).FirstOrDefault();
Without navigation properties:
var query =
from s in db.students
from c in db.Where(c => c.student == s.student).OrderByDescending(c => c.attend).Take(1)
select new joinedstudentswclass
{
class = c,
student = s
};
var datavalue = query.ToList()
If you have navigation property Classes in student class:
var query =
from s in db.students
from c in s.Classes.OrderByDescending(c => c.attend).Take(1)
select new joinedstudentswclass
{
class = c,
student = s
};
var datavalue = query.ToList()
Hello I need to crate linq query from this SQL:
SQL:
select
p.id,
p.Name,
sum(h.Hour)
from
dbo.Hour h
INNER JOIN dbo.ProjectView p ON h.ProjectId = p.Id
WHERE
h.PeopleId = 7999
group by
p.Name, p.Id
LINQ: I tried this but it is not the same:
var query = from hours in _hourRepository.GetAll()
join proj in _projectRepository.GetAll() on hours.ProjectId equals proj.Id
where hours.PeopleId == personId
group hours by new { proj.Id, proj.Name, proj.Flag, hours.Hours } into g
select new PopleProjectsSumDto
{
Id = g.Key.Id,
Name = g.Key.Name,
Flag = g.Key.Flag,
Hours = g.Sum(h => h.Hours)
};
OK i find solution by removing hours from group:
LINQ:
var query = from hours in _hourRepository.GetAll()
join proj in _projectRepository.GetAll() on hours.ProjectId equals proj.Id
where hours.PeopleId == personId
group hours by new { proj.Id, proj.Name, proj.Flag } into g
select new PopleProjectsSumDto
{
Id = g.Key.Id,
Name = g.Key.Name,
Flag = g.Key.Flag,
Hours = g.Sum(h => h.Hours)
};
I'm doing a query (see below), but I do not know how to retrieve all data from a select.
var model = new dbContext();
var query = from mp in model.matiere_premiere join req in (from stk in model.stock_mp
join ms in model.matiere_premiere
on stk.matiere_premiere_code equals
ms.code
where stk.date <= DateTime.Today
orderby stk.date descending
select new new { stk.qte, stk.matiere_premiere_code })
on mp.code equals req.matiere_premiere_code
group mp by new { mp.code } into grp
orderby grp.Key
select new
{
grp.Key,
grp.First().designation,
grp.Last().frns
};
The equivalent sql query is:
SELECT matiere_premiere.code,matiere_premiere.designation,
"matiere_premiere.unite, matiere_premiere.frns ,IF(ISNULL(REQ.qte), '0.00', REQ.qte) AS qte
FROM matiere_premiere LEFT JOIN (SELECT qte,matiere_premiere_code FROM stock_mp
JOIN matiere_premiere ON matiere_premiere.code = matiere_premiere_code
WHERE DATE <= CURRENT_DATE() ORDER BY DATE DESC)
AS REQ ON REQ.matiere_premiere_code = matiere_premiere.code
GROUP BY matiere_premiere.code ORDER BY matiere_premiere.code
it's simple, the group is also an enumerator, so you should return
select grp;
then, for each group, you can do a foreach of the values
foreach(var group in query)
{
Console.WriteLine("Key: " + group.Key);
foreach(var v in group)
{
Console.WriteLine("Value: " + v.Property);
}
}
I have a function as below :
IEnumerable<Group> GetAllChildren(int parentID)
{
using (Entities db = new Entities())
{
var result = (from x in db.Groups
where x.ParentID == parentID
select x).ToList();
foreach (Group child in result.ToList())
{
result.AddRange(GetAllChildren(child.GroupID));
}
return result;
}
}
In the above function if I pass a group name I get all the children at all levels.
It works as expected.
Now my query looks like something like :
GroupNamesWithCorrespondingEffects
= new ObservableCollection<GroupNameWithCorrespondingEffect>
(from g in db.Groups
select new GroupNameWithCorrespondingEffect
{
GroupID = g.GroupID,
GroupName = g.GroupName,
CorrespondingEffect = g.Master_Effects.Effect
}
);
The above query will give me all the groups.
Now I want to remove all the groups from GroupNamesWithCorrespondingEffects that are children of a group with id == 25.
I have tried .Remove(GetAllChildren(25)) in 2nd query. but I get following error.
Collection.Remove(GroupNameWithCorrespondingEffect) has some invalid arguments.
hope this help you:
var childs = GetAllChildren(25).ToList();
var childIDList = childs.select(u => u.GroupID).ToList();
GroupNamesWithCorrespondingEffects = GroupNamesWithCorrespondingEffects
.Where(u => !childIDList.Contains(u.GroupID)).ToList();
I have a Table(Send) with columns(Id, UserId,SendDate) and another table(Receive) with columns(Id,SendId,UserName).
I want show all records in SendTable with all RecieveUserName.
for example.
(Send)
1 1 2013
2 2 2013
(Recieve)
1 1 Jack
2 1 Ema
3 2 Alex
4 2 Sara
Result
1 1 2013 Jack, Ema
2 2 2013 Alex, Sara
I use this query in SqlServer (The DISTINCT keyword eliminates duplicate rows from the results of a SELECT statement)
SELECT DISTINCT c2.Id,
(SELECT STR( UserName )+ ','
FROM dbo.Reciver c1
WHERE c1.SendId = c2.id FOR XML PATH('')) Concatenated, c2.SendDate, c2.UserId
FROM dbo.Send AS c2 INNER JOIN
dbo.Reciver ON c2.Id = dbo.Reciver.SendId
How do this query in Linq?
Distinct is also available in LINQ.
For example
public class Product
{
public string Name { get; set; }
public int Code { get; set; }
}
Product[] products = { new Product { Name = "apple", Code = 9 },
new Product { Name = "orange", Code = 4 },
new Product { Name = "apple", Code = 10 },
new Product { Name = "lemon", Code = 9 } };
var lstDistProduct = products.Distinct();
foreach (Product p in list1)
{
Console.WriteLine(p.Code + " : " + p.Name);
}
Will return all rows.
var list1 = products.DistinctBy(x=> x.Code);
foreach (Product p in list1)
{
Console.WriteLine(p.Code + " : " + p.Name);
}
will return 9 and 4
It doesn't seem to me that you need to use Distinct in this Linq query. Assuming you have the relationships between tables set up on your linq datacontext, you can do something like this:
var result = from s in context.Send
select new {
id = s.Id,
userId = s.UserId,
date = s.SendDate,
users = s.Receive.Select(u => u.UserName)
}
Note: users will an IEnumerable<String> - you can use string.Join() on the client to join the names into a string.
Update
To return users as a string to first need to 'switch' to Linq To Objects by calling AsEnumerable() or ToList() and the Linq to Sql query.
var output = from s in result.AsEnumerable()
select new {
id = s.id,
userId = s.userId,
date = s.date,
users = string.Join(", ", s.users)
}
Also see Gert Arnolds answer for a good explanation.
What you want can only be done in two steps. Not because of the DISTINCT, but because of the FOR XML. The C# equivalent of the latter is String.Join(), but you can't use that in a linq to entities statement directly. So you must collect the required data first, then switch to linq to objects (by applying AsEnumerable) and then do the concatenation and distinct:
db.Sends
.Where(s => s.Receivers.Any())
.Select(s => new {
s.Id,
Concatenated = s.Receivers.Select(r => r.UserName)
s.SendDate,
s.UserId
})
.AsEnumerable()
.Select(x => new {
s.Id,
Concatenated = String.Join(", ", x.Concatenated)
s.SendDate,
s.UserId
})
.Distinct()