Develop Reference

Particular Query in Linq It does not perform the same thing as an inner join in SQL Server

This query is being carried out to take the zone and category names from the respective Product-related tables.
SELECT
Categoria.NombreCategoria,
Zona.ZonaGrupo,
p.NombreProducto,
p.ProductoTiene,
p.RealizadosEvento,
p.FechaInicial,
p.FechaFin
FROM
Productos p
INNER JOIN
Categoria ON p.CategoriaId = Categoria.Id
INNER JOIN
Zona ON p.ZonaId = Zona.ZonaId
The result of the SQL query returns the 1000 records that the products table must have with their zones and categories.
When doing the following in linq, it returns only 8 records ...
IQueryable<ProductosViewModel> ProductosMaped =
from p in Db.Productos
join g in Db.Zona on p.ZonaId equals g.ZonaId
join acr in Db.Categoria on p.CategoriaId equals acr.Id
select new ProductosViewModel
{
Categoria = acr.NombreCategoria,
ZonaGrupo = g.ZonaGrupo,
NombreProducto = p.NombreProducto,
ProductoTiene = p.ProductoTiene,
RealizadosEvento = p.RealizadosEvento,
FechaInicial = p.FechaInicial,
FechaFin = p.FechaFin,
};
I only need to link these 2 tables so that list only shows me CategoryName and ZoneName or Group Zone.

Better idea: Use Include with navigation properties:
List<ProductosViewModel> list = await this.Db.Productos
.Include( p => p.Zona )
.Include( p => p.Categoria )
.Where( p => p.Categoria != null && p.Zona != null ) // <-- This step may be optional depending on your database.
.Select( p => new ProductosViewModel
{
Categoria = p.Categoria.NombreCategoria,
ZonaGrupo = p.Zona.ZonaGrupo,
NombreProducto = p.NombreProducto,
ProductoTiene = p.ProductoTiene,
RealizadosEvento = p.RealizadosEvento,
FechaInicial = p.FechaInicial,
FechaFin = p.FechaFin,
} )
.ToListAsync()
.ConfigureAwait(false);

Duplicate values on join linq

I am having some problem with the results, I get duplicates instead of two with different values on the join. The db contains those two values but one of them has different value inside the text field, how come I get duplicates, the only thing that is same is the CompanyPageId).
var query = (from pageEducation in _context.PageEducations
join companyPage in _context.Pages on pageEducation.CompanyPageId equals companyPage.Id into p
from companyPage in p.DefaultIfEmpty()
where pageEducation.PageId == pageId
select new PageEducation
{
Id = pageEducation.Id,
PageId = pageEducation.PageId,
CompanyPageId = pageEducation.CompanyPageId,
CustomCompany = pageEducation.CustomCompany,
CompanyPage = companyPage != null ? new Page {Name = companyPage.Name, Id = companyPage.Id} : null,
Education = pageEducation.Education
}).ToList();
My table looks like this:
CompanyPageId, education
33 edu1
33 edu2
and the result is list with two items but duplicates.
WHen i run this query in SQL i dont get any duplicates:
select * from Page_Educations
left join Pages on page_Educations.CompanyPageId = pages.Id
where page_Educations.PageId = 10
It even working when I run the linq in LinqPad
var query = from pageEducation in Page_Educations
join companyPage in Pages on pageEducation.CompanyPageId equals companyPage.ID into p
from companyPage in p.DefaultIfEmpty()
where pageEducation.PageId == 10
select new
{
Id = pageEducation.Id,
PageId = pageEducation.PageId,
CompanyPageId = pageEducation.CompanyPageId,
CustomCompany = pageEducation.CustomCompany,
CompanyPage = companyPage != null ? new {Name = companyPage.Name, Id = companyPage.ID} : null,
Education = pageEducation.Education
};
query.Dump();

LINQ Left join Query

I am trying converting sql query into LINQ but after write query unable to fetch record from resultset
SELECT T.ServiceOrderNo,T.STATUS, T.SubStatus,T.orderVersion,T.OrderDate
,#pid, T.EventID, 'FOI'
FROM #temp1 T
LEFT JOIN Tbl_Service_Order_Progress O ON T.ServiceOrderNo DATABASE_DEFAULT = O.ServiceOrderNo
AND O.PARENTID = #pid
AND O.ServiceOrderType = 'FOI'
WHERE O.ServiceOrderNo IS NULL
Above Query following I'm trying in LINQ
var lstInsertFOI = (from i in lstFOI
join j in lstSOP on i.fulfilmentOrderItemIdentifier equals j.ServiceOrderNo into res
from subRight in res.DefaultIfEmpty()
where subRight.ParentId == parentId && subRight.ServiceOrderNo == null && subRight.ServiceOrderType.Equals("FOI")
select new
{
ServiceOrderNo = subRight.ServiceOrderNo == null ? i.fulfilmentOrderItemIdentifier : subRight.ServiceOrderNo,
EventStatus = i.status,
EventSubStatus = i.subStatus,
OrderVersion = i.orderVersion,
EVENTRECEIVEDDATE = i.orderDate,
ParentId = parentId,
EventID = i.eventID,
ServiceOrderType = "FOI",
}).ToList();
above linq query does not fetch expected result, which should return number of records from lstFOI list, but returns no record. Is the linq query correct?

Let start with SQL query.
LEFT JOIN Tbl_Service_Order_Progress O
ON T.ServiceOrderNo = O.ServiceOrderNo
AND O.PARENTID = #pid AND O.ServiceOrderType = 'FOI'
is equivalent to
LEFT JOIN (SELECT * FROM Tbl_Service_Order_Progress
WHERE PARENTID = #pid AND ServiceOrderType = 'FOI') O
ON T.ServiceOrderNo = O.ServiceOrderNo
then
WHERE O.ServiceOrderNo IS NULL
means that the query is actually using anti-join, i.e. include all the records from the left side that do not have a matching records from the right side.
With all that in mind, the equivalent LINQ query should be like this:
var lstInsertFOI = (
from i in lstFOI
join j in lstSOP
.Where(e => e.ParentId == parentId && subRight.ServiceOrderType == "FOI")
on i.fulfilmentOrderItemIdentifier equals j.ServiceOrderNo into res
where !res.Any()
select new
{
ServiceOrderNo = i.fulfilmentOrderItemIdentifier,
EventStatus = i.status,
EventSubStatus = i.subStatus,
OrderVersion = i.orderVersion,
EVENTRECEIVEDDATE = i.orderDate,
ParentId = parentId,
EventID = i.eventID,
ServiceOrderType = "FOI",
}).ToList();

associated data in linq select

I need to select data from different tables associated, I have a hospital table, another specialty, and other services, and what is held to select all hospitals and their specialties and services, there is a way to do this in linq?
this is what I'm trying
var hospitalesQuery = from hospital in App.ViewModel.ChristusDB.Hospitales
where hospital.id_tipo == "2" && hospital.christus == "1"
orderby hospital.distancia ascending
from e in App.ViewModel.ChristusDB.EspHosp
where e.fk_hospital==hospital.pk_hospital
from s in App.ViewModel.ChristusDB.ServHosp
where s.fk_hospital==hospital.pk_hospital
select new Hospitale()
{
pk_hospital = hospital.pk_hospital,
nombre = hospital.nombre,
direccion = hospital.direccion,
ciudad = hospital.ciudad,
id_ciudad = hospital.id_ciudad,
estado = hospital.estado,
id_estado = hospital.id_estado,
id_tipo = hospital.id_tipo,
tipo_descripcion = hospital.tipo_descripcion,
imagen = hospital.imagen,
gps_lat = hospital.gps_lat,
gps_lng = hospital.gps_lng,
abierto_lv = hospital.abierto_lv,
abierto_sd = hospital.abierto_sd,
telefono_1 = hospital.telefono_1,
telefono_2 = hospital.telefono_2,
telefono_3 = hospital.telefono_3,
telefono_4 = hospital.telefono_4,
telefono_5 = hospital.telefono_5,
inactivo = hospital.inactivo,
christus = hospital.christus,
especialidades= new List<Especialidade>(e),
servicios= new List<Servicio>(s)
};

You are looking for joining tables by a foreign key. LINQ (asn SQL as well) provide join for this:
from hospital in App.ViewModel.ChristusDB.Hospitales
where hospital.id_tipo == "2" && hospital.christus == "1"
join e in App.ViewModel.ChristusDB.EspHosp on hospital.pk_hospital equals e.fk_hospital
join s in App.ViewModel.ChristusDB.ServHosp on hospital.pk_hospital on s.fk_hospital
orderby hospital.distancia ascending
select new Hospitale()
{...
Update. If you want to load list dependencies for each of the hospitals, I do not think you can do this with one query in EF. This is as close as you can get:
var hospitals = (from hospital in App.ViewModel.ChristusDB.Hospitales
where hospital.id_tipo == "2" && hospital.christus == "1"
orderby hospital.distancia ascending
select new Hospitale()
{
pk_hospital = hospital.pk_hospital,
...
}).ToList();
foreach (var h in hospitals)
{
h.especialidades = App.ViewModel.ChristusDB.EspHosp.Where(e => e.fk_hospital==h.pk_hospital).ToList();
h.servicios = App.ViewModel.ChristusDB.ServHosp.Where(e => s.fk_hospital==h.pk_hospital).ToList();
}
However this would be a lot of queries to the DB, which might perform poorly. You should really think about redesigning your EF data model properly so that the framework does this job of loading dependencies for you.

I need to Optimize this Linq Query

I have a Linq query that needs optimizing.
Edit
I guess over all what I am trying to do is select all the rows in the first table, but select the last or default row in Survey, CB and Science tables...
Edit
When this creates a query, I hit the database once for the entire query and then once more for EVERY single result I get back from the first query. So if TestClass returns 30 results, I then hit the DB 30 more times for the Survey Object.
I really need a better way to make this work.
Thanks in advance!
Example Query
return (from xx in db.test
select new TestClass {
Added_By_User_ID = xx.Added_By_User_ID,
Survey = (from ru in db.Utopia
where ru.Province_ID == xx.Province_ID
orderby ru.uid descending
select ru).Take(1).ToList(),
}).ToList();
Real Query
return (from xx in db.Utopia_Province_Data_Captured_Gens
where xx.Owner_Kingdom_ID == ownerKingdomID
where kingdomList.Contains((Guid)xx.Kingdom_ID)
select new ProvinceClass
{
Kingdom_ID = xx.Kingdom_ID,
Kingdom_Island = xx.Kingdom_Island,
Kingdom_Location = xx.Kingdom_Location,
Owner_Kingdom_ID = xx.Owner_Kingdom_ID,
Province_ID = xx.Province_ID,
Province_Name = xx.Province_Name,
Owner_User_ID = xx.Owner_User_ID,
Race_ID = xx.Race_ID,
Updated_By_DateTime = xx.Updated_By_DateTime,
Networth = xx.Networth,
Land = xx.Land,
Monarch_Display = xx.Monarch_Display,
Owner = xx.Owner,
Sub_Monarch = xx.Sub_Monarch,
CB_Updated_By_Province_ID = xx.CB_Updated_By_Province_ID,
uid = xx.uid,
Formatted_By = xx.Formatted_By,
Utopian_Day_Month = xx.Utopian_Day_Month,
Utopian_Year = xx.Utopian_Year,
Ruler_Name = xx.Ruler_Name,
Personality_ID = xx.Personality_ID,
Nobility_ID = xx.Nobility_ID,
Money = xx.Money,
Daily_Income = xx.Daily_Income,
Food = xx.Food,
Runes = xx.Runes,
Population = xx.Population,
Peasents = xx.Peasents,
Peasents_Non_Percentage = xx.Peasents_Non_Percentage,
Trade_Balance = xx.Trade_Balance,
Building_Effectiveness = xx.Building_Effectiveness,
Military_Efficiency_Off = xx.Military_Efficiency_Off,
Military_Efficiency_Def = xx.Military_Efficiency_Def,
Draft = xx.Draft,
Soldiers = xx.Soldiers,
Soldiers_Regs_Off = xx.Soldiers_Regs_Off,
Soldiers_Regs_Def = xx.Soldiers_Regs_Def,
Soldiers_Elites = xx.Soldiers_Elites,
War_Horses = xx.War_Horses,
//Prisoners = xx.Prisoners,
Military_Net_Off = xx.Military_Net_Off,
Military_Net_Def = xx.Military_Net_Def,
Military_Current_Off = xx.Military_Current_Off,
Military_Current_Def = xx.Military_Current_Def,
Mil_Training = xx.Mil_Training,
Mil_Wage = xx.Mil_Wage,
Mil_Overall_Efficiency = xx.Mil_Overall_Efficiency,
Mil_Total_Generals = xx.Mil_Total_Generals,
Wizards = xx.Wizards,
Wizards_Value_Type = xx.Wizards_Value_Type,
Thieves = xx.Thieves,
Thieves_Value_Type = xx.Thieves_Value_Type,
Plague = xx.Plague,
Monarch_Vote_Province_ID = xx.Monarch_Vote_Province_ID,
Protected = xx.Protected,
Hit = xx.Hit,
Honor = xx.Honor,
Province_Notes = xx.Province_Notes,
CB_Export_Line = xx.CB_Export_Line,
Army_Out = xx.Army_Out,
Army_Out_Expires = xx.Army_Out_Expires,
Updated_By_Province_ID = xx.Updated_By_Province_ID,
SOM_Updated_By_Province_ID = xx.SOM_Updated_By_Province_ID,
SOM_Updated_By_DateTime = xx.SOM_Updated_By_DateTime,
CB_Updated_By_DateTime = xx.CB_Updated_By_DateTime,
CB_Requested = xx.CB_Requested,
CB_Requested_Province_ID = xx.CB_Requested_Province_ID,
SOM_Requested = xx.SOM_Requested,
SOM_Requested_Province_ID = xx.SOM_Requested_Province_ID,
SOS_Requested = xx.SOS_Requested,
SOS_Requested_Province_ID = xx.SOS_Requested_Province_ID,
Survey_Requested = xx.Survey_Requested,
Survey_Requested_Province_ID = xx.Survey_Requested_Province_ID,
Last_Login_For_Province = xx.Last_Login_For_Province,
Date_Time_User_ID_Linked = xx.Date_Time_User_ID_Linked,
Added_By_User_ID = xx.Added_By_User_ID,
NoteCount = (from yy in db.Utopia_Province_Notes
where yy.Province_ID == xx.Province_ID
select yy).Count(),
SOM = (from uu in db.Utopia_Province_Data_Captured_Type_Militaries
where uu.Province_ID == xx.Province_ID
where uu.Owner_Kingdom_ID == ownerKingdomID
where uu.DateTime_Added == (from ru in db.Utopia_Province_Data_Captured_Type_Militaries //datetime can be same for multiple items.
where ru.Province_ID == xx.Province_ID
where ru.Owner_Kingdom_ID == ownerKingdomID
orderby ru.uid descending // To get the last most inserted rows
select ru.DateTime_Added).FirstOrDefault()
select uu).ToList(),
SOS = (from zz in db.Utopia_Province_Data_Captured_Sciences
where ru.Province_ID == xx.Province_ID
where ru.Owner_Kingdom_ID == ownerKingdomID
orderby ru.uid descending
select ru).Take(1).ToList(),
Survey = (from ru in db.Utopia_Province_Data_Captured_Surveys
where ru.Province_ID == xx.Province_ID
where ru.Owner_Kingdom_ID == ownerKingdomID
orderby ru.uid descending
select ru).Take(1).ToList(),
CB = (from ru in db.Utopia_Province_Data_Captured_CBs
where ru.Province_ID == xx.Province_ID
where ru.Owner_Kingdom_ID == ownerKingdomID
orderby ru.uid descending
select ru).Take(1).ToList()
}).ToList();

You can select from your Utopia table and join the second one for getting the user_id like:
from ru in db.Utopia
join xx in test on ru.Province_ID equals xx.Province_ID
orderby ru.uid descending
select new TestClass
{
Added_By_User_ID = xx.Added_By_User_ID,
Survey = ru
}
Update for the real query
This is one massive query, you should consider an approach based on joins as i suggested and based on local caching as Jim McKeeth suggested. Or you should create a new table all together.
When you need to query from multiple tables with optional data, you can perform a left join:
from ru in db.Utopia
join user in db.Users on ru.UserId equals user.Id // User is required
join survey in db.Surveys on ru.Province_ID equals survey.Province_ID into j1
from survey in j1.DefaultIfEmpty() // Survey is optional (left join)
join address in db.Address on ru.UserId equals address.UserId into j2
from survey in j2.DefaultIfEmpty() // Address is optional (left join)
orderby ru.uid descending
select new TestClass
{
Added_By_User_ID = xx.Added_By_User_ID,
Survey = survey,
Street = address.Street,
UserName = new UserName
{
FirstName = user.FirstName,
LastName = user.LastName
}
}
Be aware that the amount of joins will influence the performance of your query. Sooner or later it will become more efficient do find a better way with caching.
Another note is that calling ToList() in your query will actually execute that part of the query (or the whole query).

Something like:
from xx in db.test
join ru in db.Utopia on xx.Province_ID equals ru.Province_ID
orderby ru.uid descending
select new ..

The complexity of your real query to me indicates you should be moving this LINQ statement into a stored procedure, then calling that instead.
I recommend this because (a) you will have complete control over the how the query executes and, (b) profiling and performance optimizing your query is much easier in TSQL. This is the strategy we have used in larger projects in the past when result-set generation becomes non-trivial.
I would also suggest you use AutoMapper to perform the task of transferring the sproc results into your DTO, because you appear to have a near 1:1 mapping