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Linq left join with multiple tables

Hi I am developing web application in .net. I have come across with below scenario.
Below is my first table.
perm_levelid scrn_id perm_id perm_read perm_write
40 1 2 1 1
41 2 2 1 1
42 3 2 1 1
Below is my second table.
scrn_id scrn_name
1 UserProfile
2 Change Password
3 Dashboard
4 Lease request
The relation between above two table is scrn_id
The output i am expecting is
scrn_id perm_id perm_read perm_write
1 2 1 1
2 2 1 1
3 2 1 1
4 0 0 0
I want total 4 rows in the result. scrn_id 1,2,3 matching in both tables so i should retrieve first table perm_read and perm_write values. Remaining value from 2 nd table also i want to get.
I tried as below.
List<screendetails> obj = new List<screendetails>();
obj = (from c in db.rolsp_perm_levelmapping
join mapdetails in db.rolsp_scrn_screen on c.scrn_id equals mapdetails.scrn_id
into mapObj
from wt in mapObj.DefaultIfEmpty()
where c.perm_id== permisssionID
select new screendetails {
scrn_id=c.scrn_id,
scrn_name= wt.scrn_name,
Read=c.perm_read,
Write=c.perm_write
}).ToList();
return obj;
Above query does not yields correct result. May i get some help here to fix this? Thank you

obj= (from scrn in db.rolsp_scrn_screen
from rmap in db.rolsp_perm_levelmapping
.Where(rl=>rl.scrn_id==scrn_id).DefaultIfEmpty() select new screendetails {
scrn_id=scrn.scrn_id,
scrn_name= scrn.scrn_name,
Read=rmap.perm_read,
Write=rmap.perm_write
}).ToList();
Try using this... Hope this helps...

Linq where on include

I'm stuck with this linq query.
I've this tables.
ID A B C D
1 some data
2 some other data
Then, For every record on that table I may have none or many rows
ID TableA_ID R
1 1 1
2 1 2
3 1 5
4 2 2
For example. Row 1 (some data) has 3 rows on table B.
I tried using
tableA.Include(x => x.tablebchilds.Where( d => d.R == 1)).ToList()
but it is not working. With many others varation.
The objective of this query is to return tableA.row #1 if I pass it 1 as value (value of R). Number <> 2 won't give any result.
Tables are linked on EF. So TableB.tableA_ID is Foreign key of tableA.ID
Edit #1
I tried the answers in the question marked as duplicated with no luck. Give that 2 tableA.rows if the user insert 1 as parameter, linq query should return Row #1, some data. If 2 is passed as parameter, nothing is return.
A working SQL statement is:
SELECT [TableA].* FROM [TableA] JOIN [TableB] ON [TableA].[Id] = [TableB].[TableA_Id] WHERE [TableB].[R] = 1
Thanks!

If you have database relationship properly configured this have to work.
tableA.Include(x => x.tableBChilds).Where(tableA => tableA.tableBChilds.Any(b => b.R== 1)).ToList();

Grouping records that haven't groups values

Please consider this records:
Id Week Value
-----------------------------
1 1 1000
2 1 1200
3 2 800
4 3 1800
5 3 1100
6 3 1000
I want to group records for 4 weeks but we haven't record for week 4.For Example:
Week Count
---------------------
1 2
2 1
3 3
4 0
How I can do this with linq?
Thanks

First you need an array of weeks then this query might help
var weeks = new List<int>{1,2,3,4}
var q = from w in weeks
join rw in (
from r in table
group r by r.Week into g
select new {week = g.Key, count = g.Count()}) on w equals rw.week into p
from x2 in p.DefaultIfEmpty()
select new {w, count = (x2 != null ? x2.count : 0)};
online result in .net fiddle

You can try
var result = Enumerable.Range(1, 4)
.GroupJoin(table,
week => week,
record => record.Week,
(week, records) => new { Week = week, Count = records.Count() });
As suggested by jessehouwing, the Enumerable.Range will return the possible week numbers to be used as left outer keys within the join.
GroupJoin will then accept as parameters
A lambda/delegate/method that returns the left outer key
A lambda/delegate/method that extracts the right key from your table.
A lambda/delegate/method that builds an item of the result.
Regards,
Daniele.

c# linq to entities using method based queries - trying to select where the object appears only once

i have got this table that relates the Table hardware with a table Process..
this table is called processHardware.
this table is discribed by:
IDProcessHardware
IDProcess
IDHardware
State
the field state can have 3 states (1-Insert, 2-Remove,3-Substitute)..
so i can i have this:
IDProcessoHardware IDProcesso IDHardware State
1 10 1 1
2 10 2 1
3 10 1 2
what this tell me is that the hardware with id 1 was insert on the process with the id 10
then the user insert the hardware with id 2 on the process with the id 10, and the it remove the hardware with the id 1 from the process with the id 10
by giving the id of the process i want to get the id of the hardware that were insert, this is, the id of the hardware that were remove..
so in this case the record that i will get is record number 2..because was insert, but was not removed..
after getting the ids from this table i need to relate the ids with the table hardware, this table is described by idhardware, serial number, description..
i was using linq method base..
and this was something that i did, but didnt go further after this..
var ProcessoHardware = from procHardware in db.ProcessoHardwares
where procHardware.Rem == 0 && procHardware.IDProcesso == IDProcesso
group procHardware by procHardware.IDHardware into g
select new { IDHardware = g.Key, count = g.Count() };
the query above didnt work for me...
so i want to get the records that appears only once on the table, and then relate the ids that were obtained from this query and get the info about those ids like, serial number, description(these fields are on a table called Hardware).
thanks in advance..
in sql i manage to do the query ..
SELECT *
FROM
(SELECT IDHardware ,COUNT(IDHardware) nu
FROM dbo.ProcessoHardware
WHERE IDProcesso=47
Group By IDHardware) T WHERE nu=1
how do i pass this to linq?

Firstly your SQL statement would be clearer if you used the having clause so it becomes
SELECT IDHardware, COUNT(IDHardware) nu
FROM dbo.ProcessoHardware
WHERE IDProcesso=47
GROUP BY IDHardware
HAVING COUNT(IDHardware) = 1
secondly, your SQL statement doesn't mention a field called Rem, but your LINQ states where procHardware.Rem == 0. I'm going to assume that you need to keep that filter. If so then all you need to do is add a where clause to count your group, g. Try the following
var ProcessoHardware = from procHardware in db.ProcessoHardwares
where procHardware.Rem == 0 && procHardware.IDProcesso == IDProcesso
group procHardware by procHardware.IDHardware into g
where g.Count() == 1
select new { IDHardware = g.Key, count = g.Count() };
although the literal transformation of your statement (without the Rem and hard coded ID of 47) to LINQ would be
var ProcessoHardware = from procHardware in db.ProcessoHardwares
where procHardware.IDProcesso == 47
group procHardware by procHardware.IDHardware into g
where g.Count() == 1
select new { IDHardware = g.Key, count = g.Count() };

Populating an ObservableCollection of ObservableCollection, delimited by two database columns

My database is as follows :
ID Date Number NumberIWishToRecord
What I wish to do is use a Linq-to-SQL query to populate an ObservableCollection<ObservableCollection<CustomClass>>.
What I want is select only the rows were Number == a given parameter.
ID refers to a person, what I want to do is get all the information about a person and store it in an ObservableCollection, so I will have an ObservableCollection<CustomClass>, with each CustomClass holding information about only one row, and each ObservableCollection<CustomClass> holding information about only one person (recorded on different days).
I then wish to select an ObservableCollection of the ObservableCollection<CustomClass> which will hold information on all people!
So, some sample data :
ID Date Number NumberIWishToRecord
1 27-06-2012 0.1933 25
1 28-06-2012 0.1933 27
1 29-06-2012 0.1933 29
2 14-06-2012 0.1933 412
2 15-06-2012 0.1741 321
So when I run my method, I want to return only the Numbers of the given parameter, in my case I will choose 0.1933.
I then want both rows where ID = 1 to be saved in an ObservableCollection<CustomClass>, and the single row where ID == 2 to be saved in another ObservableCollection<CustomClass>. Then, both of these ObservableCollections will be held in their own ObservableCollection! To illustrate :
ObservableCollection<ObservableCollection<CustomClass>>
ObservableCollection<CustomClass>
1 27-06-2012 0.1933 25
1 28-06-2012 0.1933 27
1 29-06-2012 0.1933 29
ObservableCollection<CustomClass>
2 14-06-2012 0.1933 412
How would I write a query in linq to sql that would do this ?

I'll just write a standard query syntax Linq expression to achieve this, you adapt it for your tables.
var rowsById = new ObservableCollection<ObservableCollection<row>>(
from r in _rows
where r.number == 1.2
group r by r.ID into rowIdGroup
select new ObservableCollection<row>(rowIdGroup));
If you need to convert data from the row into the CustomClass:
var rowsById = new ObservableCollection<ObservableCollection<CustomClass>>(
from r in _rows
where r.number == 1.2
group r by r.ID into rowIdGroup
select new ObservableCollection<CustomClass>(
rowIdGroup.Select(r => new CustomClass
{
ID = r.ID,
Number = r.number // add more
})));
Or if you prefer query syntax in all the expression:
var rowsById = new ObservableCollection<ObservableCollection<CustomClass>>(
from r in _rows
where r.number == 1.2
group r by r.ID into rowIdGroup
select new ObservableCollection<CustomClass>(
from gr in rowIdGroup select new CustomClass
{
ID = gr.ID,
Number = gr.number
}));