i have two linq - sql queries, and im wondering how to join them..
First Query
var ab = from a in Items_worker.getCEAItems()
where a.ProjectCode == lbl_projectCode.Text
select new
{
a.ID
};
Second Query
var j = from c in tblInc_worker.get(c => c.MarginID == MarginID && c.IncTypeID == "CAPEX")
orderby c.DateCreated
select c.ID;
First Query would return:
fasf-1212-1212-1212-1212
afaa-1414-1414-1414-1414
Second Query would return:
fasf-1212-1212-1212-1212
afaa-1414-1414-1414-1414
0000-0000-0000-0000-0000
1111-1111-1111-1111-1111
question is how can i possibly join the two table. Wherein the second query should return all of the records with the same ID found in the first query plus the id containing "0000-0000-0000-0000-0000" second query..
The result should be:
fasf-1212-1212-1212-1212
afaa-1414-1414-1414-1414
0000-0000-0000-0000-0000
You can use union to join the both queries, for example split your second query in two with conditions like :
var ab = from a in Items_worker.getCEAItems()
where a.ProjectCode == lbl_projectCode.Text
select new
{
a.ID
};
var j = from c in tblInc_worker.get(c => c.MarginID == MarginID && c.IncTypeID == "CAPEX")
orderby c.DateCreated
select c.ID where c.ID.Equals("0000-0000-0000-0000-0000");
var j1 = from c in tblInc_worker.get(c => c.MarginID == MarginID && c.IncTypeID == "CAPEX")
orderby c.DateCreated
select c.ID where !(c.ID.Equals("0000-0000-0000-0000-0000"));
var result = ab.Union(j.Union(j1));
Hope this helps..
Related
If the person you are searching is a CIA emplyee, take his CIAJobs.EmployerID, otherwise select People.ID
SELECT
case when CIAJobs.EmployeeID IS NULL then People.ID
else CIAJobs.EmployerID
end
FROM [FMO].[People] AS p
LEFT JOIN [FMO].[CIAJobs] j
ON (p.ID = j.[EmployeeID])
AND (j.[relationshipType] = '25a8d79d-377e-4108-8c92-0ef9a2e1ab63')
where p.ID = '1b66e032-94b2-e811-96e0-f48c508e38a2' // id of person you search for
OR
j.[EmployeeID] = '1b66e032-94b2-e811-96e0-f48c508e38a2' // id of person you search for
I tried doing this in Linq:
var a = from l in People
join x in CIAJobs
on l.Id equals x.EmployeeID && x.RelationshipTypeGuid equals Guid.Parse('25a8d79d-377e-4108-8c92-0ef9a2e1ab63')
into gcomplex
from xx in gcomplex.DefaultIfEmpty()
select (xx.EmployeeID == null) ? l.EmployeeId : x.EmployerID;
var b = a.ToList();
why does the query show an error because of this chunk: && x.RelationshipTypeGuid equals Guid.Parse('25a8d79d-377e-4108-8c92-0ef9a2e1ab63')
If I remove this part it shows no error.
Error is: operator && cannot be applied to operands of type Guid and Guid.
Can you help me correct the Linq query please logically and syntactically? Thank you.
You don't need join for multiple conditions in this scenario. Use this
var a = from l in People
join x in CIAJobs
.Where(z=>z.RelationshipTypeGuid
.Equals(Guid.Parse('25a8d79d-377e-4108-8c92-0ef9a2e1ab63')))
on l.Id equals x.EmployeeID
into gcomplex
from xx in gcomplex.DefaultIfEmpty()
select (xx.EmployeeID == null) ? l.EmployeeId : x.EmployerID;
var b = a.ToList();
But based on your problem statement this should do
var a = from l in People
join x in CIAJobs
on l.Id equals x.EmployeeID
into gcomplex
from xx in gcomplex.DefaultIfEmpty()
select (xx == null) ? l.EmployeeId : xx.EmployerID;
var b = a.ToList();
I am sql query us producing correct result, but when i'm doing the same in LINQ. Output is incorrect. Please let me know where my making mistake.
Following linq query that i created.
LINQ Query:
List<UserModel> Model = (from users in db.UserM
join ct in db.CustT on users.UserId equals ct.UserID into group1
from g1 in group1.DefaultIfEmpty()
join ti in db.TestIn on g1.TestId equals ti.TestID into group2
from g2 in group2.DefaultIfEmpty()
where (users.CustomerId==CustomerId) && (users.RoleId == 4) && (users.Status == 1)
group new
{
g2.TestInvitationID,
g2.TestID,
}
by new
{
users.FirstName,
users.CreatedOn,
users.Email,
users.UserId
} into group4
select new UserModel
{
Name = group4.Key.FirstName,
CreatedOn = group4.Key.CreatedOn,
EmailId = group4.Key.Email,
UserId = group4.Key.UserId,
NoOfTestTaken = group4.Select(x=>x.TestID).Distinct().Count(),
NoOfInvitationsSent = group4.Count(x => x.TestInvitationID != 0)
}).ToList();
SQL Query:
SELECT IsNull(COUNT(distinct TS.TestId),0) AS NoOfTests,
IsNull(COUNT(TS.TestInvitationID),0) AS NoOfInvitations,
UM.Email,
UM.UserId,
UM.FirstName,
UM.CreatedOn
FROM UserM as UM
left JOIN CustT AS CT
ON UM.UserId=CT.UserId
left JOIN TestIn AS TS
ON TS.TestId = CT.TestId
WHERE UM.CustomerId=41
AND UM.RoleId=4
and UM.[Status]=1
GROUP BY UM.UserId, UM.Email, UM.FirstName, UM.CreatedOn
Tables:
"UserM" - columns: UserId, Email, FirstName, CreatedOn
"CustT" - columns: TestId, UserId,
"TestIn" - columns: TestInvitationId, TestId
The difference between SQL COUNT(expr) and LINQ Count is that the former excludes NULL values, which produces a difference when used on right side of a left outer join with no matching records (SQL will produce 0 while LINQ 1). The closest LINQ equivalent is Count(expr != null).
So the direct translation of your SQL query would be like this (note that the generated SQL query could and most likely will be different):
(A side note: When converting SQL query to LINQ, it's good to use the same aliases to make it easier to see the mappings)
var query =
from um in db.UserMasters
join ct in db.CustTests on um.UserId equals ct.UserID
into ctGroup from ct in ctGroup.DefaultIfEmpty() // left outer join
join ts in db.TestInvitaions on ct.TestId equals ts.TestID
into tsGroup from ts in tsGroup.DefaultIfEmpty() // left outer join
where um.CustomerId == UserSession.CustomerId
&& um.RoleId == 4
&& um.Status == 1
group ts by new { um.UserId, um.Email, um.FirstName, um.CreatedOn } into g
select new UserModel
{
Name = g.Key.FirstName,
CreatedOn = g.Key.CreatedOn,
EmailId = g.Key.Email,
UserId = g.Key.UserId,
NoOfTestTaken = g.Where(ts => ts != null).Select(ts => ts.TestID).Distinct().Count(),
NoOfInvitationsSent = g.Count(ts => ts != null)
};
var result = query.ToList();
I suspect that the following row is the problem because is not the same like in your sql:
Linq:
NoOfInvitationsSent = group4.Count(x => x.TestInvitationID != 0)
SQL:
IsNull(COUNT(TS.TestInvitationID),0) AS NoOfInvitations
Due to counting items from a left join Linq should be instead:
NoOfInvitationsSent = group4.Where(i => i != null).Count()
To put it all together, with a bit of better formatting:
var model = (from users in db.UserMasters
join ct in db.CustTests on users.UserId equals ct.UserID into group1
from ct in group1.DefaultIfEmpty()
join ti in db.TestInvitaions on ct.TestId equals ti.TestID into group2
from ct in group2.DefaultIfEmpty()
where users.CustomerId == UserSession.CustomerId &&
users.RoleId == 4 &&
users.Status == 1
group new { ct.TestInvitationID, ct.TestID }
by new
{
users.FirstName,
users.CreatedOn,
users.Email,
users.UserId
} into grouping
select new UserModel
{
Name = grouping.Key.FirstName,
CreatedOn = grouping.Key.CreatedOn,
EmailId = grouping.Key.Email,
UserId = grouping.Key.UserId,
NoOfTestTaken = grouping.Where(i => i != null).Select(x => x.TestID).Distinct().Count(),
NoOfInvitationsSent = grouping.Where(i => i != null).Count()
}).ToList();
i plan to join 2 table, and get the distinct value of language column. How should i achieve that in Linq? I try add 'group' but no luck. Besides, i want to select s value too together with r distinct language value.
My code:
public ActionResult QuestionLink(int Survey_ID)
{
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model
on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
group r.language << this is not work **
select r;
return PartialView(query.ToList());
}
This is what in MoreLinq is called DistinctBy. But if that method works on IEnumerable, so you can't use it in an EF query. But you can use the same approach:
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
group new { r, s } by r.language into grp
select grp.FirstOrDefault();
But I wonder if this really is what you want. The result depends on the ordering of languages that the database happens to return. I think you should add a predicate for a specific language and remove the grouping:
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model
on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
&& r.language == someVariable
select new { r, s };
You can do like this:
var query = from r in db.SURV_Question_Ext_Model
join s in db.SURV_Question_Model
on r.Qext_Question_ID equals s.Question_ID
where s.Question_Survey_ID == Survey_ID
group new {r, s} by r.language into rg
select rg.Key;
I have one Linq Query. When I run the query, Only for 10 records its taking 13 seconds to extract the data to the model. I need to know the query which I wrote is good for performance or not. Please guide me what i am doing wrong.
Code
var stocktakelist = (from a in Db.Stocktakes
select new ExportStock
{
Id = a.Id,
ItemNo = a.ItemNo,
AdminId = (from admin in Db.AdminAccounts where admin.Id == a.Id select admin.Name).FirstOrDefault(),
CreatedOn = a.CreatedOn,
Status = (from items in Db.Items where items.ItemNo == a.ItemNo select items.ItemStatu.Description).FirstOrDefault(),
Title = (from tit in Db.BibContents where tit.BibId == (from bibs in Db.Items where bibs.ItemNo == a.ItemNo select bibs.BibId).FirstOrDefault() && tit.TagNo == "245" && tit.Sfld == "a" select tit.Value).FirstOrDefault() // This line of Query only makes the performance Issue
}
).ToList();
Thanks
The reason this is so slow is because it is running the 3 inner LINQ statements for every item in the outer LINQ statement.
Using LINQ joins will run only 4 queries and then link them together, which is faster.
To find out how to join, there are plenty of resources on the Internet depending on the type of LINQ you are using.
If you're retrieving this data from a SQL server, perhaps consider doing this intensive work in SQL - this is what SQL was designed for and it's much quicker than .NET. EDIT: As highlighted below, the work is done in SQL if using LINQ to SQL/Entities and using the correct join syntax.
I was trying to create the corresponding query with some joins for practice.
I cannot test it and i'm not 100% sure that this query will you get the result
you are hoping for but maybe at least it will give you a hint on how to write
joins with linq.
from a in Db.Stocktakes
join admin in Db.AdminAccounts
on a.Id equals admin.Id
into adminJoinData
from adminJoinRecord in adminJoinData.DefaultIfEmpty( )
join items in Db.Items
on a.ItemNo equals items.ItemNo
into itemsJoinData
from itemsJoinRecord in itemsJoinData.DefaultIfEmpty( )
join title in Db.BibContents
(
from subQuery in Db.BibContents
where subQuery.TagNo == "245"
where subQuery.Sfld == "a"
select subquery
)
on title.BibId equals itemsJoinRecord.BidId
into titleJoinData
from titleJoinRecord in titleJoinData.DefaultIfEmpty( )
select new ExportStock( )
{
Id = a.Id,
ItemNo = a.ItemNo,
AdminId = adminJoinRecord.Name,
CreatedOn = a.CreatedOn,
Status = itemsJoinRecord.ImemStatu.Description,
Title = titleJoinRecord.Value
}
As others have said, you should use Left Outer Joins in your LINQ just as you would if writing it in SQL.
Your query above will end up looking roughly like this once converted (this is untested, but gives the basic idea):
var a = from a in Db.Stocktakes
join admin in Db.AdminAccounts on admin.Id equals a.Id into tmpAdmin
from ad in tmpAdmin.DefaultIfEmpty()
join item in Db.Items on item.ItemNo equals a.ItemNo into tmpItem
from it in tmpItem.DefaultIfEmpty()
join title in Db.BibContents on bib.BibId equals items.BibId into tmpTitle
from ti in tmpTitle.DefaultIfEmpty()
where ti.TagNo == "245"
&& ti.Sfld == "a"
select new ExportStock
{
Id = a.Id,
ItemNo = a.ItemNo,
AdminId = ad == null ? default(int?) : ad.Id,
CreatedOn = a.CreatedOn,
Status = it == null ? default(string) : it.ItemStatus.Description,
Title = ti == null ? default(string) : ti.Value
};
Using lambda expressions your query will look like this:
Db.Stocktakes
.Join(Db.AdminAccounts, a => a.Id, b => b.Id, (a,b) => new { a, AdminId = b.Name })
.Join(Db.Items, a => a.ItemNo, b => b.ItemNo, (a,b) => new { a, Status = b.ItemStatus.Description, BidId = b.BibId })
.Join(Db.BibContents, a => a.BibId, b => b.BibId, (a,b) => new { a, Value = b.Value, TagNo = b.TagNo, Sfld = b.Sfld })
.Where(a => a.TagNo == "245" && a.Sfld == "a")
.Select(a =>
new ExportStock { Id = a.Id,
ItemNo = a.ItemNo,
AdminId = a.AdminId,
CreatedOn = a.CreatedOn,
Status = a.Status,
Title = a.Value
}
).ToList();
I would like to join results from a table, to sum up the results from a where condition on 2 different rows, as this code:
var a = (from o in _DB.Services
where (o.description.Contains(searchText) || o.nom.Contains(searchText))
orderby o.date
select new { results = ?????, id = ?????? }).Take(maxResults).ToList();
What can I put, in order to take into account the results=???? and id=???
Thanks
Based on your comment, can't you just do the following?
var a = (from o in _DB.Services
where (o.description.Contains(searchText) || o.nom.Contains(searchText))
orderby o.date
select new
{
results = o.description,
id = o.nom
})
.Take(maxResults)
.ToList();