Case1:
var query = (from p in db.TblPost where (from q in db.TblThread
where q.LocationLocationid == locationID && q.CategoriesCategoryid == categoryID select q.Threadid).Contains(p.ThreadThreadid)
join r in db.TblThread on p.ThreadThreadid equals r.Threadid join s in db.TblUser on p.UserUserid equals s.Userid join t
in db.TblCategories on r.CategoriesCategoryid equals t.Categoryid join u in db.TblLocation on r.LocationLocationid
equals u.Locationid orderby r.CreatedTime descending
select new { p, r.Subject, r.EventAddress, r.EventClosetime, r.EventDate, r.EventDuration, r.EventStarttime,
r.EventTitle, r.IseventAllday, r.TargetUsers, r.CreatedTime, s.FirstName, s.MiddleName, s.LastName, t.Name,
u.Locationname, r.Isreadonly }).ToList();
OR
Case 2:
List<TblPost> _tblPost = new List<TblPost>();
_tblPost = (from p in db.TblPost select p).ToList();
List<TblThread> _tblThread = new List<TblThread>();
_tblThread = (from p in db.TblThread select p).ToList();
List<TblUser> _tblUser = new List<TblUser>();
_tblUser = (from p in db.TblUser select p).ToList();
List<TblLocation> _tblLocation = new List<TblLocation>();
_tblLocation = (from p in db.TblLocation select p).ToList();
List<TblCategories> _tblCategory = new List<TblCategories>();
_tblCategory = (from p in db.TblCategories select p).ToList();
var query = (from p in _tblPost where (from q in _tblThread where q.LocationLocationid == locationID
&& q.CategoriesCategoryid == categoryID select q.Threadid).Contains(p.ThreadThreadid) join r in _tblThread on p.ThreadThreadid
equals r.Threadid join s in _tblUser on p.UserUserid equals s.Userid join t in _tblCategory on r.CategoriesCategoryid equals
t.Categoryid join u in _tblLocation on r.LocationLocationid equals u.Locationid orderby r.CreatedTime descending
select new { p, r.Subject, r.EventAddress, r.EventClosetime, r.EventDate, r.EventDuration, r.EventStarttime,
r.EventTitle, r.IseventAllday, r.TargetUsers, r.CreatedTime, s.FirstName, s.MiddleName, s.LastName,
t.Name, u.Locationname, r.Isreadonly }).ToList();
I've these two codes which results the same. But, in case 2 i'm getting the result some quickly as compared to case 1. Which one should i need to follow?
Shall i follow case 2? is it right way to get huge data in Web.API?
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();
SELECT ra.ResidentID, ra.RoomID, r.Number, ra.StartDate, p.FacilityID
FROM(
SELECT ResidentID, MAX(StartDate) AS max_start
FROM RoomAssignments
GROUP BY ResidentID
) m
INNER JOIN RoomAssignments ra
ON ra.ResidentID = m.ResidentID
AND ra.StartDate = m.max_start
INNER JOIN Rooms r
ON r.ID = ra.RoomID
INNER JOIN Person p
ON p.ID = ra.ResidentID
inner join ComplianceStage cs
ON cs.Id = p.ComplianceStageID
ORDER BY ra.EndDate DESC
I'm trying to figure out how to convert this to C# using LINQ. I'm brand new with C# and LINQ and can't get my subquery to fire correctly. Any chance one of you wizards can turn the lights on for me?
Update-----------------
I think I've got the jist of it, but am having trouble querying for the max startdate:
var maxQuery =
from mra in RoomAssignments
group mra by mra.ResidentID
select new { mra.ResidentID, mra.StartDate.Max() };
from ra in RoomAssignments
join r in Rooms on ra.RoomID equals r.ID
join p in Persons on ra.ResidentID equals p.ID
where ra.ResidentID == maxQuery.ResidentID
where ra.StartDate == maxQuery.StartDate
orderby ra.ResidentID, ra.StartDate descending
select new {ra.ResidentID, ra.RoomID, r.Number, ra.StartDate, p.FacilityID}
Following my LINQ to SQL Recipe, the conversion is pretty straight forward if you just follow the SQL. The only tricky part is joining the range variable from the subquery for max start date to a new anonymous object from RoomAssignments that matches the field names.
var maxQuery = from mra in RoomAssignments
group mra by mra.ResidentID into mrag
select new { ResidentID = mrag.Key, MaxStart = mrag.Max(mra => mra.StartDate) };
var ans = from m in maxQuery
join ra in RoomAssignments on m equals new { ra.ResidentID, MaxStart = ra.StartDate }
join r in Rooms on ra.RoomID equals r.ID
join p in Persons on ra.ResidentID equals p.ID
join cs in ComplianceStage on p.ComplianceStageID equals cs.Id
orderby ra.EndDate descending
select new {
ra.ResidentID,
ra.RoomID,
r.Number,
ra.StartDate,
p.FacilityID
};
I am trying to convert a SQL statement to LINQ.
I have this as SQL:
SELECT mutDetail.*
FROM hallo.Mutatie as mut
JOIN hallo.MutatieDetail AS mutDetail ON mut.MutatieID = mutDetail.fkMutatieID
JOIN tblMedewerker AS med ON med.MedewerkerID = mut.fkMedewerkerID
JOIN tblKlant AS klant ON klant.KlantID = med.fkKlantID
WHERE mutDetail.BronCode = 'Personeelsnummer'
AND klant.KlantNummer = '78555522'
And this is my LINQ statement:
public IQueryable<Mutatie> GetMutatiesInstroom()
{
var mutaties = (from m in context.Mutatie
join mutDetail in context.MutatieDetail on m.MutatieID equals mutDetail.fkMutatieID
join med in context.tblMedewerker on m.fkMedewerkerID equals med.MedewerkerID
join klant in context.tblKlant on med.fkKlantID equals klant.KlantID
select m);
return mutaties;
}
But how to write the where statement in LINQ?
Thank you
I don't know what the problem was, but isn't it simple? Before select m:
where m.BronCode == "Personeelsnummer" && klant.KlantNummer == "8700"
Complete query as requested:
var mutaties = from m in context.Mutatie
join mutDetail in context.MutatieDetail on m.MutatieID equals mutDetail.fkMutatieID
join med in context.tblMedewerker on m.fkMedewerkerID equals med.MedewerkerID
join klant in context.tblKlant on med.fkKlantID equals klant.KlantID
where m.BronCode == "Personeelsnummer" && klant.KlantNummer == "8700"
select m;
It should go here:
public IQueryable<Mutatie> GetMutatiesInstroom()
{
var mutaties = (from m in context.Mutatie
join mutDetail in context.MutatieDetail on m.MutatieID equals mutDetail.fkMutatieID
join med in context.tblMedewerker on m.fkMedewerkerID equals med.MedewerkerID
join klant in context.tblKlant on med.fkKlantID equals klant.KlantID
where (mutDetail.BronCode == "Personeelsnummer" &&
klant.KlantNummer == "8700")
select m);
return mutaties;
}
Here is an example from microsofts documentation on how to add a filter in Linq statement.
var queryLondonCustomers = from cust in customers
where cust.City == "London"
select cust;
https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/basic-linq-query-operations
right under section Filtering
So I have few tables and i want inner join it information two create
new object. But I have a little bit trouble.
One my table have connection one to many, and when linq request , it
give me more result than i want , he just copy information. I need
request something like this:
IPagedList<HelperListings> srch = (from l in db.gp_listing
where l.DateCreated > weekago
join lp in db.gp_listing_photo on l.Id equals lp.ListingId
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings { id = l.Id, HouseNumber = l.HouseNumber,ListingPrice = l.ListingPrice, PhotoUrl = lp.PhotoUrl.First(), AreaStateCode = loc.AreaStateCode }).ToList().ToPagedList(page ?? 1, 15);
PhotoUrl = lp.PhotoUrl.First() i need something like this but i don`t have any ideas how to do it. Need ur help guys.
UPDATE :
Responding to your comment, you have at least 2 options : 1. use group by and select only the first PhotoUrl from each group, or 2. don't join to gp_listing_photo table to avoid duplicated rows, and use subquery to get only the first PhotoUrl. Example for the latter :
IPagedList<HelperListings> srch =
(from l in db.gp_listing
where l.DateCreated > weekago
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings
{
id = l.Id,
HouseNumber = l.HouseNumber,
ListingPrice = l.ListingPrice,
PhotoUrl = (from lp in db.gp_listing_photo where l.Id = lp.ListingId select lp.PhotoUrl).FirstOrDefault(),
AreaStateCode = loc.AreaStateCode
}
).ToList().ToPagedList(page ?? 1, 15);
How about simply appending .Distinct() after your LINQ query to avoid duplicated data :
IPagedList<HelperListings> srch =
(from l in db.gp_listing
where l.DateCreated > weekago
join lp in db.gp_listing_photo on l.Id equals lp.ListingId
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings
{
id = l.Id,
HouseNumber = l.HouseNumber,
ListingPrice = l.ListingPrice,
PhotoUrl = lp.PhotoUrl,
AreaStateCode = loc.AreaStateCode
}
).Distinct().ToList().ToPagedList(page ?? 1, 15);
For Reference : LINQ Select Distinct with Anonymous Types
I am unable to execute the below linq.
var items( from p in Patients
join q in MURWorksheets on p.PatientId equals q.PatientId into step1
from s in step1.DefaultIfEmpty()
join t in MURWorksheetAnswers on s.MURWorksheetId equals t.MURWorksheetId into step2
from s2 in step2.DefaultIfEmpty()
select new {p.FirstName , Date = (s.MURDate == null ? DateTime.Now.Date : s.MURDate),
s2.MURQuestionnaireId,s2.MURExpctedAnswersId}).ToList();
Here is the sql for the same for your reference.
select a.FirstName,b.MURDate,c.MURQuestionnaireId,c.MURWorksheetAnswersID from Patients as a
left join MURWorksheet as b on a.PatientId = b.PatientId
left join MURWorksheetAnswers as c on b.MURWorksheetId = c.MURWorksheetId
You are missing an equals sign in your pasted code:
var items = (from p in Patients
join q in MURWorksheets on p.PatientId equals q.PatientId into step1
from s in step1.DefaultIfEmpty()
join t in MURWorksheetAnswers on s.MURWorksheetId equals t.MURWorksheetId into step2
from s2 in step2.DefaultIfEmpty()
select new {p.FirstName , Date = (s.MURDate == null ? DateTime.Now.Date : s.MURDate),
s2.MURQuestionnaireId,s2.MURExpctedAnswersId}).ToList();