We Keep Coding

Linq join tables using a flag column

I need join 3 tables using a column flag called cashbillingtype_id, this determines what table will joined.
For example i have this Datatable called [CashBillings]:
cashbilling_id cashbillingtype_id
1 1
2 1
3 2
When:
cashbillingtype_id = 1 means: CashBillingsBills
cashbillingtype_id = 2 means: CashBillingsReturns
cashbillingtype_id = 3 means: CashBillingsCancellations
Now each table (Bills, Returns, Cancellations) have inside a column called cashbillingBRC_total i need to get this column data according the flag main datatable.
I Tryed:
(from CashBillings in _DataTable_Billings.AsEnumerable()
join CashBillingsTypes in _DataTable_BillingsTypes.AsEnumerable()
on CashBillings.Field<Int32>("cashbillingtype_id") equals CashBillingsTypes.Field<Int32>("cashbillingtype_id")
select new
{
cashbilling_id = CashBillings.Field<Int32>("cashbilling_id"),
cashbillingBRC_total = (CashBillingsTypes.Field<Int32>("cashbillingtype_id") == 1 ?
(from CashBillingsBills in _DataTable_BillingsBills.AsEnumerable()
where CashBillingsBills.Field<Int32>("cashbilling_id") == CashBillings.Field<Int32>("cashbilling_id")
select CashBillingsBills.Field<Double>("cashbillingbill_total")).LastOrDefault()
:
(CashBillingsTypes.Field<Int32>("cashbillingtype_id") == 2 ?
(from CashBillingsReturns in _DataTable_BillingsReturns.AsEnumerable()
where CashBillingsReturns.Field<Int32>("cashbilling_id") == CashBillings.Field<Int32>("cashbilling_id")
where CashBillingsReturns.Field<Int32>("cashbillingreturnstatus_id") == 1 // Only Processed
select CashBillingsReturns.Field<Double>("cashbillingreturn_total")).LastOrDefault()
:
(from CashBillingsCancellations in _DataTable_BillingsCancellations.AsEnumerable()
where CashBillingsCancellations.Field<Int32>("cashbilling_id") == CashBillings.Field<Int32>("cashbilling_id")
select CashBillingsCancellations.Field<Double>("cashbillingcancellation_total")).LastOrDefault())
),
}).Aggregate(DataTable_Billings, (dt, result) => { dt.Rows.Add(result.cashbilling_id,
result.cashbillingtype_id,
result.cashbillingtype_name,
result.cashbillingBRCstatus_id,
result.cashbillingBRCstatus_name,
result.cashbillingcustomer_fullname,
result.cellar_name,
result.cashbillingBRC_subtotal,
result.cashbillingBRC_discount,
result.cashbillingBRC_isv,
result.cashbillingBRC_total,
result.cashbillingBRC_date); return dt;
});
But this code is very very low efficient.

Can you check with left joining all tables initially and just operating on fields in select statement?
In case you require information on left join, see here

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() };

EF Query Help - Grouping and Sub queries

I have data table (DOCs, which is the DBSet in my context) with below data
ID Code Rev
1 A1 1
2 A1 2
3 A1 3
4 A3 1
5 A2 1
6 A2 2
I need to select the records which has a records for each Code which has the highest Rev. My expected result is
ID Code Rev
3 A1 3
6 A2 2
4 A3 1
The ID column is the PK of the table and Code+Rev is unique.
Note: There are other fields in the table which i need to get for the result. Ideal would be to get a iqueryable (Doc is the model class), i was think of selecting the ID within an inner query and then use that to get the iqueryable of docs.
Thanks in Advance

Try this:
var res = from r in DOCs
where (from c in DOCs
group c by c.Code into g
select new {
localCode = g.Key,
localRev = g.Max(t => t.Rev)
}).Any(x => x.localCode == r.Code && x.localRev == r.Rev)
select r;
res is IQueryable.

Linq Query for EAV design table

I had a situation to use EAV design tables and I am new to this design,I am struck with a select query. Below is my query structure and data.
TABLE1:
Id KeyName
1 Name
2 Age
TABLE2:
ID TABLE1_ID VALUE
1 1 ABC
2 2 12
3 1 CDF
4 2 14
5 1 XYZ
6 2 13
7 1 CSF
8 2 10
EXPECTED OUTPUT: Get all the values which are greater than 12 AND Value contains "C".
i.e.,
Table2_ID Result Table1_KeyName
1 ABC Name
2 12 Age
3 CDF Name
4 14 Age
Options I tried are:
Var temp = (from c in Table2
where c.Value > 12 && c.Table1.KeyName.Contains("C")
Select new
{
ID = c.ID,
Result = C.Value
});
the above query didn't returned any result, as filters(in where clause) are across rows. I even tried "OR" condition in where clause, it returns me everything. Please do help me.

Your query is wrong, did you type it in here or copy and paste it from your work?
Do you have this table setup in an ORM such as Entity Framework? So that there is a relationship setup between table1 and table2, so you don't have to 'join' them?
To be more 'correct' it should be...
Var temp = (from c in Table2
where c.Value > 12 && c.Table1.Name.Contains("C")
Select new
{
ID = c.ID,
Name = c.Table1.Name,
Value = c.Value
});
Or if the relationship isn't in an ORM your using explicitly specify the join as follows:
Var temp = (from c in Table2
join c1 in Table1 on c.Table1_ID equals c1.Id
where c.Value > 12 && c.Table1.Name.Contains("C")
Select new
{
ID = c.ID,
Name = c.Table1.Name,
Value = c.Value
});
Edit: then it should be an OR, not AND
Var temp = (from c in Table2
where c.Value > 12 || c.Value.Contains("C")
Select new
{
ID = c.ID,
Result = c.Value,
KeyName = c.Table1.Name
});

Get the next and previous sql row by Id and Name, EF?

Assume we have the following data in a SQL Server table (sorted by name) :
Id Name LName
-------------------------
5 Abbas Dayyan
3 Mohammad KD
4 Nima Ahmad
1 Omid Zangene
2 Pedram Ahmadi
we have an Id query string and we wanna get the next and previous row (if exists) from Id.
e.g :
the Id query string is 4, so we wanna get Mohammad KD as previous row and Omid Zangene as next row.
Could you please guide me how can do it with LINQ to Entity Framework.
Edit:
In practice the number of table rows is around 1 million.
Table rows didn't sort by Name by default, wa need to sort them by Name for the result.

How about this?
var result = (from person in db.People
where person.Id == id
let ordered = db.People.OrderBy(p => p.Name)
let reversed = db.People.OrderByDescending(p => p.Name)
let previous = reversed.SkipWhile(p => p.Id != id).Skip(1).FirstOrDefault()
let next = ordered.SkipWhile(p => p.Id != id).Skip(1).FirstOrDefault()
select new { previous, next }).First();
Edit: Took the new specifications into account.
Edit 2: Modified the code to not use LastOrDefault, which doesn't work with LINQ to Entities.

Try this:
int id = 4;
var list = (from x in ctx.Table
where x.id >= id - 1 && x.id <= id + 1
select x).OrderBy(o -> o.name).ToList();
edit: this will return elements with ID 3,4 and 5. I dont know if you are actually ordering the table in the database by name, but if you are i think it would be easier to just use a loop instead of using linq to get the previous and next element.
update: sorted the result by name