I am getting data from multiple tables by joining and i want to group data on particular column value but after group by statement i can access my aliases and their properties. What mistake i am making?
public List<PatientHistory> GetPatientHistory(long prid)
{
using(var db = new bc_limsEntities())
{
List<PatientHistory> result =
(from r in db.dc_tresult
join t in db.dc_tp_test on r.testid equals t.TestId into x
from t in x.DefaultIfEmpty()
join a in db.dc_tp_attributes on r.attributeid equals a.AttributeId into y
from a in y.DefaultIfEmpty()
where r.prid == prid
group new {r,t,a} by new {r.testid} into g
select new PatientHistory
{
resultid = r.resultid,
bookingid = r.bookingid,
testid = r.testid,
prid = r.prid,
attributeid = r.attributeid,
result = r.result,
Test_Name = t.Test_Name,
Attribute_Name = a.Attribute_Name,
enteredon = r.enteredon,
Attribute_Type = a.Attribute_Type
}).ToList();
return result;
}
}
You're doing this wrong way. As been said by Jon after grouping the sequences with aliases r,t,a doesn't exist. After grouping you receive the sequence g with sequances of r,t,a in each element of g. If you want get one object from each group (for example most recent) you should try this:
List<PatientHistory> result =
(from r in db.dc_tresult
join t in db.dc_tp_test on r.testid equals t.TestId into x
from t in x.DefaultIfEmpty()
join a in db.dc_tp_attributes on r.attributeid equals a.AttributeId into y
from a in y.DefaultIfEmpty()
where r.prid == prid
group new {r,t,a} by new {r.testid} into g
select new PatientHistory
{
resultid = g.Select(x => x.r.resultid).Last(), // if you expect single value get it with Single()
// .... here add the rest properties
Attribute_Type = g.Select(x => x.a.Attribute_Type).Last()
}).ToList();
I appreciated this question so I thought I would add another potential usage case. I would like feedback on what the cleanest approach is to getting table information through a group operation so that I can project later in the select operation. I ended up combining what the OP did which is to pass objects into his group clause and then used the g.Select approach suggested by YD1m to get table information out later. I have a LEFT JOIN so I'm defending against nulls :
// SQL Query
//DECLARE #idCamp as Integer = 1
//
//select *,
//(select
//count(idActivityMaster)
//FROM tbActivityMasters
//WHERE dftidActivityCategory = A.idActivityCategory) as masterCount
//FROM tbactivitycategories A
//WHERE idcamp = #idCamp
//ORDER BY CategoryName
int idCamp = 1;
var desiredResult =
(from c in tbActivityCategories
.Where(w => w.idCamp == idCamp)
from m in tbActivityMasters
.Where(m => m.dftidActivityCategory == c.idActivityCategory)
.DefaultIfEmpty() // LEFT OUTER JOIN
where c.idCamp == idCamp
group new {c, m} by new { m.dftidActivityCategory } into g
select new
{
idActivityCategory = g.Select(x => x.m == null ? 0 : x.m.dftidActivityCategory).First(),
idCamp = g.Select(x => x.c.idCamp).First(),
CategoryName = g.Select(x => x.c.CategoryName).First(),
CategoryDescription = g.Select(x => x.c.CategoryDescription).First(),
masterCount = g.Count(x => x.m != null)
}).OrderBy(o=> o.idActivityCategory);
desiredResult.Dump("desiredResult");
If I just use a basic group approach I get the results but not the extra column information. At least I can't find it once I group.
var simpleGroup = (from c in tbActivityCategories
.Where(w => w.idCamp == idCamp)
.OrderBy(o => o.CategoryName)
from m in tbActivityMasters
.Where(m => m.dftidActivityCategory == c.idActivityCategory)
.DefaultIfEmpty() // LEFT OUTER JOIN
where c.idCamp == idCamp
group m by m == null ? 0 : m.dftidActivityCategory into g
select new
{
// How do I best get the extra desired column information from other tables that I had before grouping
// but still have the benefit of the grouping?
// idActivityCategory = g.Select(x => x.m == null ? 0 : x.m.dftidActivityCategory).First(),
// idCamp = g.Select(x => x.c.idCamp).First(),
// CategoryName = g.Select(x => x.c.CategoryName).First(),
// CategoryDescription = g.Select(x => x.c.CategoryDescription).First(),
// masterCount = g.Count(x => x.m != null)
idActivityCategory = g.Key,
masterCount = g.Count(x => x != null)
});
simpleGroup.Dump("simpleGroup");
Please tear this up. I'm trying to learn and it just seems like I'm missing the big picture here. Thanks.
UPDATE : Cleaned up by moving the work into the group and making the select more straight forward. If I had known this yesterday then this would have been my original answer to the OP question.
int idCamp = 1;
var desiredResult =
(from c in tbActivityCategories
.Where(w => w.idCamp == idCamp)
from m in tbActivityMasters
.Where(m => m.dftidActivityCategory == c.idActivityCategory)
.DefaultIfEmpty() // LEFT OUTER JOIN
where c.idCamp == idCamp
group new { c, m } by new
{ idActivityCategory = m == null ? 0 : m.dftidActivityCategory,
idCamp = c.idCamp,
CateGoryName = c.CategoryName,
CategoryDescription = c.CategoryDescription
} into g
select new
{
idActivityCategory = g.Key.idActivityCategory,
idCamp = g.Key.idCamp,
CategoryName = g.Key.CateGoryName,
CategoryDescription = g.Key.CategoryDescription,
masterCount = g.Count(x => x.m != null)
}).OrderBy(o => o.idActivityCategory);
desiredResult.Dump("desiredResult");
Related
Wondering why LINQ doesn't have a Left Join method. I've been trying to figure this out with myriad examples on SO, but no such luck. The other examples show simple examples with one join. If I group the joins then I only get references to the TradeCountries table in the select statement.
Being new to LINQ, I could've had this done 4 hours ago with a simple SELECT statement, but here I'm am trying to figure out why the LeftJoin method was left out of LINQ.
What does the line with "LeftJoin" need to be changed to make this work?
/*
* GetTop5Distributors
#param int array of series IDs
*/
public List<TopDistributors> Get5TopDistributors(IEnumerable<int> seriesIds)
{
_context = new MySQLDatabaseContext();
var result = _context.TradesTrades
.Join(_context.TradesSeries, tt => tt.SeriesId, ts => ts.Id, (tt, ts) => new { tt, ts })
.Join(_context.TradesTradeDistributors, tsd => tsd.tt.Id, ttd => ttd.TradeId,
(tsd, ttd) => new { tsd, ttd })
.Join(_context.TradesOrganisations, tsdto => tsdto.ttd.DistributorId, to => to.Id,
(tsdto, to) => new { tsdto, to })
.LeftJoin(_context.TradesCountries, tsdc => tsdc.to.CountryId, tc => tc.Id,
(tsdc, tc) => new {tsdc, tc})
.Where(x => seriesIds.Contains(x.tsdc.tsdto.tsd.tt.SeriesId))
.Where(x => x.tsdc.tsdto.tsd.tt.FirstPartyId == null)
.Where(x => x.tsdc.tsdto.tsd.tt.Status != "closed")
.Where(x => x.tsdc.tsdto.tsd.tt.Status != "cancelled")
.GroupBy(n => new { n.tsdc.tsdto.tsd.tt.SeriesId, n.tsdc.tsdto.ttd.DistributorId })
.Select(g =>
new TopDistributors
{
SeriesId = g.Key.SeriesId,
DistributorName = g.Select(i => i.tsdc.to.Name).Distinct().First(),
IsinNickname = g.Select(i => i.tsdc.tsdto.tsd.ts.Nickname).Distinct().First(),
CountryName = g.Select(i => i.tc.Name).Distinct().First(),
CommissionTotal = Math.Ceiling(g.Sum(i => i.tsdc.tsdto.ttd.Commission))
}
)
.OrderByDescending(x => x.CommissionTotal)
.Take(5)
.ToList();
return result;
}
Here's the rather simple select statement that is taking orders or magnitude too long to convert to LINQ.
SELECT
trades_trades.series_id,
trades_organisations.`name`,
trades_series.nickname,
trades_countries.name as Country_Name,
SUM(trades_trade_distributors.commission) as Commission_Total
FROM
trades_trades
JOIN trades_series
ON trades_series.id = trades_trades.series_id
JOIN trades_trade_distributors
ON trades_trades.id = trades_trade_distributors.trade_id
JOIN trades_organisations
ON trades_trade_distributors.distributor_id = trades_organisations.id
LEFT JOIN trades_countries
ON trades_organisations.country_id = trades_countries.id
WHERE trades_trades.series_id IN (
17,
18)
AND trades_trades.first_party_id IS NULL
AND trades_trades.status <> 'closed'
AND trades_trades.status <> 'cancelled'
GROUP BY trades_trades.series_id, trades_trade_distributors.distributor_id
ORDER BY Commission_Total DESC
Following my recipe, here is a more or less straightforward translation of the SQL to LINQ. I moved the where to be near what it constrains, and used let to create a convenient name for the Sum, as LINQ doesn't allow you to forward reference anonymous object members.
var ans = from tt in trades_trades
where new[] { 17, 18 }.Contains(tt.series_id) && tt.first_party_id == null &&
tt.status != "closed" && tt.status != "cancelled"
join ts in trades_series on tt.series_id equals ts.id
join ttd in trades_trade_distributors on tt.id equals ttd.trade_id
join to in trades_orginizations on ttd.distributor_id equals to.id
join tc in trades_countries on to.country_id equals tc.id into tcj
from tc in tcj.DefaultIfEmpty() // GroupJoin -> left join
group new { tt, ts, ttd, to, tc } by new { tt.series_id, ttd.distributor_id } into tradeg
let Commission_Total = tradeg.Sum(trade => trade.ttd.commission)
orderby Commission_Total descending
select new {
tradeg.Key.series_id,
tradeg.First().to.name,
tradeg.First().ts.nickname,
Country_Name = tradeg.First().tc == null ? null : tradeg.First().tc.name,
Commission_Total
};
I've been trying to left join the table and they are in a one-to-many relationship.
I have written a SQL query and trying to convert it into LINQ for my ASP.NET Core application.
My sql query is as follows:
SELECT ap.SystemId,
ap.AccessRequiredToId,
cb.AccessAreaManagementId,
ap.EquipmentTagId,
COUNT(ap.Name) [Count]
FROM ApplicationForms ap LEFT JOIN AccessAreaCheckBoxes cb
ON n ap.RecordId = cb.RecordId
WHERE EndDate IS NULL AND (Checked IS NULL OR Checked = 1)
GROUP BY ap.SystemId, ap.AccessRequiredToId, cb.AccessAreaManagementId, ap.EquipmentTagId
SQL Result
And my LINQ is as follows:
var active = _context.ApplicationForms
.Where(w => w.EndDate == null)
.GroupJoin(_context.AccessAreaCheckBoxes
.Where(w => (w.AccessAreaManagement == null || w.Checked == true)),
x => x.RecordId,
y => y.RecordId,
(x, y) => new { ApplicationForms = x, AccessAreaCheckBoxes = y })
.SelectMany(x => x.AccessAreaCheckBoxes.DefaultIfEmpty(),
(x, y) => new { x.ApplicationForms, AccessAreaCheckBoxes = y })
.GroupBy(g => new { g.ApplicationForms.System, g.ApplicationForms.AccessRequiredTo, g.AccessAreaCheckBoxes.AccessAreaManagement, g.ApplicationForms.EquipmentTag })
.Select(s => new RecordViewModel
{
System = s.Key.System.Name,
AccessRequiredTo = s.Key.AccessRequiredTo.Name,
AccessArea = s.Key.AccessAreaManagement.Name,
EquipmentTag = s.Key.EquipmentTag.Name,
Count = s.Count()
}).ToList();
Everything is working well except it doesn't show the rows with the NULL value.
Did I miss out something in my LINQ?
Any help would be greatly appreciated!
This is what I do in the end, post here for your reference.
var active = (from ap in _context.ApplicationForms
join cb in _context.AccessAreaCheckBoxes
on ap.RecordId equals cb.RecordId into j1
from j2 in j1.DefaultIfEmpty()
where ap.EndDate == null
&& (j2.AccessAreaManagement == null || j2.Checked == true)
group new { ap.System, ap.AccessRequiredTo, j2.AccessAreaManagement, ap.EquipmentTag }
by new { System = ap.System.Name, Building = ap.AccessRequiredTo.Name, AccessArea = j2.AccessAreaManagement.Name, Equipment = ap.EquipmentTag.Name } into grp
select new RecordViewModel
{
System = grp.Key.System,
AccessRequiredTo = grp.Key.Building,
AccessArea = grp.Key.AccessArea,
EquipmentTag = grp.Key.Equipment,
Count = grp.Count()
}).ToList();
My linq query is:
var query1 = (from grp in ctnx.tblGroupDatas
group grp by grp.MeterID_FK into g
let maxId = g.Max(gId => gId.GroupDataID)
select new { metId = g.Key, maxId });
query2 = (from met in ctnx.tblMet
from mod in ctnx.tblMod.Where(mo => mo.ModID == met.Mod_FK).DefaultIfEmpty()
from grp in ctnx.tblGroupDatas.Where(gr => gr.Met_FK == met.MetID)
from group1 in db.tblMetRelateGroups.Where(x => x.Met_FK == met.MetID)
from q1 in query1.Where(q => q.metId == met.MetID && grp.GroupDataID == q.maxId)
where (group1.GroupMetID_FK == groupID)
select new
{
met.MetID,
mod.ModSerial,
met.MetSerial,
met.MetWaterSharingNo,
met.MetPowerSharingNo,
grp.GroupDate,
grp.GroupDataID
});
var gridobisdata = query2.OrderByDescending(m => m.GroupDate);
but this show error:
The specified LINQ expression contains references to queries that are
associated with different contexts.
I have set of Users and Visits. (So user do visits)
Visit have User navigation property.
I need to find the users who don't visit.
I can do this by finding the users who visit, finding all of the users then taking the difference.
I was trying to find a solution which is faster.
This is what I have right now:
var users = _db.Users.AsNoTracking().Include(c => c.City).Where(x => x.City.Id == city);
var groupedUsers = _db.Visits.AsNoTracking().Include(c => c.City).Include(a=>a.VisitedBy).Where(x => x.City.Id == city).GroupBy(x => x.VisitedBy).Select(group => new { VisitedBy = group.Key, Count = group.Count() });
var visitingUsers = groupedUsers.Select(user => user.VisitedBy);
var dif = users.Except(visitingUsers);
However I was trying GroupJoin as below:
var results = _db.Users.Include(c => c.City).Where(c => c.City.Id == city).
GroupJoin(_db.Visits.Include(c => c.City).Include(u => u.VisitedBy), u => u.Id, v => v.VisitedBy.Id, (u, v) => new { User = u , Visits = v })
.Select(o=>o.User);
But this gives me all of the Users, I want the users who don't exist in the Visit set.
Any help?
You may be able to avoid the correlated sub-query in the other answer by actually doing the left join with null check. Here's a quick example:
var A = new [] { new Foo { Bar = 1 }, new Foo { Bar = 2 }};
var B = new [] { new Foo { Bar = 2 }};
var C = from x in A
join y in B on x.Bar equals y.Bar into z
from y in z.DefaultIfEmpty()
where y == null
select x;
Check the emitted SQL...
I am not too sure if the city filtering is what you are after however the following should achieve what you desire:
var visitsToCity = _db.Visits.Where(v => v.City.Id == city);
var usersOfCity = _db.Users.Where(u => u.City.Id == city);
var nonVisitingUsers = usersOfCity.Where(u => !visitsToCity.Any(v => v.VisitedBy == u));
The last Where combined with the Any should result in a SQL statement like:
SELECT * FROM Users u WHERE u.CityId = #p0 AND
NOT EXISTS(SELECT 1 FROM Visits v WHERE v.CityId = #p0 AND
v.VisitedById = u.Id)
Where #p0 will be supplied with the value of city.
I have this sql query that does exactly what i want but i need it in linq. It returns a few AVC rows and counts how many PersonAVCPermission that has status 1 linked to it
SELECT a.Id, a.Name, a.Address, COUNT(p.AVCID) AS Count
FROM AVC AS a
LEFT OUTER JOIN
(
SELECT PersonAVCPermission.AVCId
FROM PersonAVCPermission
WHERE PersonAVCPermission.Status = 1
) AS p
ON a.Id = p.AVCId
GROUP BY a.Id, a.Name, a.Address
I have this query in linq and it does the same thing except when there are no PersonAVCPermission it still counts 1
var yellows = odc.PersonAVCPermissions.Where(o => o.Status == (int)AVCStatus.Yellow);
var q = from a in odc.AVCs
from p in yellows.Where(o => o.AVCId == a.Id).DefaultIfEmpty()
group a by new { a.Id, a.Name, a.Address } into agroup
select new AVCListItem
{
Id = agroup.Key.Id,
Name = agroup.Key.Name,
Address = agroup.Key.Address,
Count = agroup.Count(o => o.Id != null)
};
Im guessing that with DefaultIfEmpty() it places null rows in the list that then gets counted so i try to exclude them with (o => o.Id != null) but it still counts everything as at least one
If i dont use DefaultIfEmpty() it skips the rows with count 0 completely
How can i exclude them or am i doing it completely wrong?
How about using .Any() and a Let?
var yellows = odc.PersonAVCPermissions.Where(o => o.Status == (int)AVCStatus.Yellow);
var q = from a in odc.AVCs
let Y = (from p in yellows.Where(o => o.AVCId == a.Id) select p).Any()
where Y == true
group a by new { a.Id, a.Name, a.Address } into agroup
select new AVCListItem
{
Id = agroup.Key.Id,
Name = agroup.Key.Name,
Address = agroup.Key.Address,
Count = agroup.Count(o => o.Id != null)
};
You don't need the join, nor the grouping:
var q = from a in odc.AVCs
select new AVCListItem
{
Id = a.Id,
Name = a.Name,
Address = a.Address,
Count = yellows.Where(o => o.AVCId == a.Id).Count()
};