I want to do a subquery with linq but it doesn't work. :-( I've searched google for an answer, but I don't know how to solve the problem.
This is my sql
string strSQL = #"SELECT a.ident, a.ben1
FROM pwdata a
WHERE a.iid = (SELECT max(b.iid) FROM pwdata b WHERE b.ident = a.ident)";
That's how I tried to do with Linq, but this is not the right way
var query = from i in maxxContext.pwdata
where i.IID = (SELECT max(b.iid) FROM pwdata b WHERE b.ident = a.ident)
orderby i.ident
select new CompareParts
{
PartNumber = i.ident,
PartName = i.ben1
};
return query.ToList().Distinct();
Can anyone of you help me?
It's not clear why you've started intermingling LINQ with regular SQL. It doesn't work like that.
This should work though:
var query = from i in maxxContext.pwdata
where i.IID == (pwdata.Where(b => b.ident == i.ident)
.Max(b => b.iid))
orderby i.ident
select new CompareParts
{
PartNumber = i.ident,
PartName = i.ben1
};
Alternatively, you could do a join:
var query = from i in maxxContext.pwdata
join b in pwdata on i.ident equals b.ident into bs
where i.IID == bs.Max(b => b.iid)
orderby i.ident
select new CompareParts
{
PartNumber = i.ident,
PartName = i.ben1
};
Related
I have a situation where two tables should be joined with multiple columns with or condition. Here, I have a sample of sql query but i was not able to convert it into linq query.
select cm.* from Customer cm
inner join #temp tmp
on cm.CustomerCode = tmp.NewNLKNo or cm.OldAcNo = tmp.OldNLKNo
This is how i have write linq query
await (from cm in Context.CustomerMaster
join li in list.PortalCustomerDetailViewModel
on new { OldNLKNo = cm.OldAcNo, NewNLKNo = cm.CustomerCode } equals new { OldNLKNo = li.OldNLKNo, NewNLKNo = li.NewNLKNo }
select new CustomerInfoViewModel
{
CustomerId = cm.Id,
CustomerCode = cm.CustomerCode,
CustomerFullName = cm.CustomerFullName,
OldCustomerCode = cm.OldCustomerCode,
IsCorporateCustomer = cm.IsCorporateCustomer
}).ToListAsync();
But this query doesn't returns as expected. How do I convert this sql query into linq.
Thank you
You didn't tell if list.PortalCustomerDetailViewModel is some information in the database, or in your local process. It seems that this is in your local process, your query will have to transfer it to the database (maybe that is why it is Tmp in your SQL?)
Requirement: give me all properties of a CustomerMaster for all CustomerMasters where exists at least one PortalCustomerDetailViewModel where
customerMaster.CustomerCode == portalCustomerDetailViewModel.NewNLKNo
|| customerMaster.OldAcNo == portalCustomerDetailViewModel.OldNLKNo
You can't use a normal Join, because a Join works with an AND, you want to work with OR
What you could do, is Select all CustomerMasters where there is any PortalCustomerDetailViewModel that fulfills the provided OR:
I only transfer those properties of list.PortalCustomerDetailViewModel to the database that I need to use in the OR expression:
var checkProperties = list.PortalCustomerDetailViewModel
.Select(portalCustomerDetail => new
{
NewNlkNo = portalCustomerDetail.NewNlkNo,
OldNLKNo = portalCustomerDetail.OldNLKNo,
});
var result = dbContext.CustomerMasters.Where(customerMaster =>
checkProperties.Where(checkProperty =>
customerMaster.CustomerCode == checkProperty.NewNLKNo
|| customerMaster.OldAcNo == checkProperty.OldNLKNo)).Any()))
.Select(customerMaster => new CustomerInfoViewModel
{
Id = customerMaster.Id,
Name = customerMaster.Name,
...
});
In words: from each portalCustomerDetail in list.PortalCustomerDetailViewModel, extract the properties NewNKLNo and OldNLKNo.
Then from the table of CustomerMasters, keep only those customerMasters that have at least one portalCustomerDetail with the properties as described in the OR statement.
From every remaining CustomerMasters, create one new CustomerInfoViewModel containing properties ...
select cm.* from Customer cm
inner join #temp tmp
on cm.CustomerCode = tmp.NewNLKNo or cm.OldAcNo = tmp.OldNLKNo
You don't have to use the join syntax. Adding the predicates in a where clause could get the same result. Try to use the following code:
await (from cm in Context.CustomerMaster
from li in list.PortalCustomerDetailViewModel
where cm.CustomerCode == li.NewNLKNo || cm.OldAcNo = li.OldNLKNo
select new CustomerInfoViewModel
{
CustomerId = cm.Id,
CustomerCode = cm.CustomerCode,
CustomerFullName = cm.CustomerFullName,
OldCustomerCode = cm.OldCustomerCode,
IsCorporateCustomer = cm.IsCorporateCustomer
}).ToListAsync();
var result=_db.Customer
.groupjoin(_db.#temp ,jc=>jc.CustomerCode,c=> c.NewNLKNo,(jc,c)=>{jc,c=c.firstordefault()})
.groupjoin(_db.#temp ,jc2=>jc2.OldAcNo,c2=> c2.OldNLKNo,(jc2,c2)=>{jc2,c2=c2.firstordefault()})
.select(x=> new{
//as you want
}).distinct().tolist();
I have the following query that I would like to translate to linq.
SELECT
SUM(Credits.CreditAmount)
,Transactions.Id
,Person.FullName
,Person.Id
FROM
Person
JOIN
Transactions
ON Person.AccountId = Transactions.AccountId
JOIN Credits
ON Transactions.Id = Credits.TransactionId
WHERE
Person.Type = 'AccountHolder'
AND Person.Status = 'Active'
AND Transactions.CancelledDate IS NULL
AND Credits.CancelledDate IS NULL
GROUP BY Transactions.AccountId, Person.FullName, Person.Id
HAVING SUM(Credits.CreditAmount) > 20
This is what I came up with. It's an absolute pig... The SQL it generates must be awful.
var query = from p in Person
join t in Transactions
on p.AccountId equalas t.AccountId
join c in Credits
on t.TransactionId = c.TransactionId
where p.Status == "Active" &&
p.Type = "AccountHolder" &&
t.CancelledDate == null &&
c.CancelledDate == null
group new { c.CreditAmount, t.AccountId, p.FullName, p.Id } by new { t.AccountId, p.FullName, p.SSN } into grp
let sumC = grp.Select(x => x.CreditAmount).Sum()
select new
{
TotalCredit = sumC,
AccountId = grp.Key.AccountId,
FullName = grp.Key.FullName,
Id = grp.Key.Id
};
query.Where(p => p.TotalServiceCredit > 20);
The SQL query runs in approximately 3 seconds but I have yet to find the patience to let the Linq query finish. I was wondering if there is something different I should be doing to accomplish this "group, sum, having" query I'm trying to write? Is there something I can do to help Linq generate more performat SQL?
UPDATE
Turns out sgmoore had the right idea. The key to the performance issue was in his answer.
The difference between this
let sumC = grp.Select(x => x.CreditAmount).Sum()
and this
TotalCredit = grp.Sum(x => x.CreditAmount)
was the difference between a query that finishes and one that does not.
See my revised LINQ query below which completes in about the same time as the SQL (5.3 seconds for SQL vs 5.6 seconds for LINQ).
var query = from p in Person
join t in Transactions
on p.AccountId equalas t.AccountId
join c in Credits
on t.TransactionId = c.TransactionId
where p.Status == "Active" &&
p.Type = "AccountHolder" &&
t.CancelledDate == null &&
c.CancelledDate == null
group new { c.CreditAmount, t.AccountId, p.FullName, p.Id } by new { t.AccountId, p.FullName, p.SSN } into grp
select new
{
TotalCredit = grp.Sum(x => x.CreditAmount),
AccountId = grp.Key.AccountId,
FullName = grp.Key.FullName,
Id = grp.Key.Id
};
query.Where(p => p.TotalServiceCredit > 20);
Thanks for all your help!
I don't disagree with WEI_DBA's comment but if you need to do this, then you might find it easier to break this into several queries, eg
var query1 = from p in Person
join t in Transactions on p.AccountId equals t.AccountId
join c in Credits on t.TransactionId equals c.TransactionId
where p.Status == "Active" &&
p.Type = "AccountHolder" &&
t.CancelledDate == null &&
c.CancelledDate == null
select new { c.CreditAmount, t.AccountID, p.FullName, p.Id};
var query2 = (from p in query1
group p by new { p.AccountId, p.FullName, p.Id } into grp
select new
{
TotalCredit = grp.Sum(x => x.CreditAmount),
AccountId = grp.Key.AccountId,
FullName = grp.Key.FullName,
Id = grp.Key.Id
};
var query3 = (from p in query2 where p.TotalCredit > 20 select p);
Then you can let LINQ combine this into one sql command.
As always, it is a good idea to check and verify the actual TSQL generated.
I know there are probably a ton of questions like this already but i'm having trouble
select *
from [Group]
where GroupId not in
(select GroupId
from CustomerGroup
where CustomerId = 189621)
i have myGroups = db.Groups.Where(e=> e.GroupId), but how do i say not in?
i am kind of there
var myGroups = from a in db.Groups
where!(from b in db.CustomerGroups
where b.CustomerId == customer.CustomerId )
var groupIds = from cg in db.CustomerGroups
where cg.CustomerId == 189621
select cg.GroupId;
var myGroups = from g in db.Groups
where !groupIds.Contains(g.GroupId)
select g;
Need a list to disqualify first. NOT IN is basically a !(IEnumerable).Contains() in LINQ (since you're comparing to a set).
Using lambda expression, you probably can do it like this
var groupIds = db.CustomerGroups.Where(x => x.CustomerId == 189621).Select(x => x.GroupId);
var myGroups = db.CustomerGroups.Where(x => !groupIds.Contains(x.GroupId)).ToList();
Can anyone help me to translate my sql query to linq? I am not so good in linq can anyone help me out with it please .
select
s.UploadFilename ,
a.ID,
isnull(s.Status_id,1) as 'Status_id' ,
a.CaseID,
a.RecordType,
a.ColumnName,
a.FieldName,
a.OldValue,
a.NewValue,
a.ModifiedBy,
A.ModifiedOn,
isnull(u.UserName,'') as 'UserName'
from [dbo].[AuditTrail] as A
left join Case_Status as s
on s.Case_Id=A.CaseID
left join [dbo].[User] as u
on a.ModifiedOn =u.UserID
where A.CaseID=5338
This is not the answer, my query is big, it was not accepting this query as comment.
This query is not returning records :
var AuditTrailFile = (from AT in db.AuditTrails
join ATCS in db.AssnAuditTrailCaseStatus
on new {ID = AT.ID} equals new { ID = (int)(ATCS.AuditTrialID) }
into ATCS_join
from ATCS in ATCS_join.DefaultIfEmpty()
join CS in db.Case_Status on new { Case_StatusId = (int)(ATCS.CaseStatusID) }
equals new { Case_StatusId = CS.Case_StatusId } into CS_join
from CS in CS_join.DefaultIfEmpty()
where
AT.CaseID == CaseID
orderby
AT.ModifiedOn descending
select new
{
ID = (int?)AT.ID,
Case_StatusId = CS.Case_StatusId != null ? CS.Case_StatusId : 1, //Case_StatusId comes for row whose FieldName=Status Else No Case_StatusId
AT.CaseID,
AT.RecordType,
AT.ColumnName,
AT.FieldName,
AT.OldValue,
AT.NewValue,
AT.ModifiedBy,
UserName = AT.User != null ? AT.User.UserName : "",
AT.ModifiedOn,
UploadFilename = CS.UploadFilename
}).ToList();
var q = (from Labels in dc.tblArtworkDataLabels select Labels).ToList();
But I need this to do the quivalent of:
SELECT d.ID, d.labelID, d.dataID, d.data, l.templateID
FROM tblArtworkDataLabels AS d INNER JOIN
tblArtworkData AS l ON d.dataID = l.ID
WHERE (l.templateID = 238)
How do I do this in LINQ?
Edit
Sorry! Missed the WHERE clause on original statmenet!
var result = dc.tblArtworkDataLabels
.Join(dc.tblArtworkData, l => l.ID, d => d.dataID, (l, d) => new {l, d})
.Select(o => new {
Id = o.d.ID,
LabelId = o.d.labelID,
DataId = o.d.dataID,
Data = o.d.data,
TemplateId = o.l.templateID,
})
.Where(o => o.l.templateID == 238);
If you have a correct foreign key on tblArtworkData to the primary key on the tblArtworkDataLabels and have imported them correctly into the DBML designer you can have LINQ2SQL implicitly creating the join:
from l in tblArtworkData
where l.templateID = 238
select new {
Id = l.tblArtworkDataLabel.ID,
LabelId = l.tblArtworkDataLabel.labelID,
DataId = l.tblArtworkDataLabel.dataID,
Data = l.tblArtworkDataLabel.data,
TemplateId = l.templateID,
}
See my answer on the question "LINQ to SQL: Multiple joins ON multiple Columns. Is this possible?" for how the implicit join translates to SQL.
Edit:
In the case I misunderstood your relations and you have many tblArtworkDataLabels to one tblArtworkData you have to turn the query the other way around
from d in tblArtworkDataLabels
where d.tblArtworkData.templateID = 238
select new {
Id = d.ID,
LabelId = d.labelID,
DataId = d.dataID,
Data = d.data,
TemplateId = d.tblArtworkData.templateID,
}
try
var q = (from Labels in dc.tblArtworkDataLabels
join data in dc.tblArtworkData on Labels.ID equals data.DataID select Labels).ToList();