I'm trying to join few tables using LINQ and retrieve a data set. But my problem is when I group the tables, I cannot access the fields of the non grouped tables in the LINQ query. here is my sample code block. Please help
var query = from sb in db.Surfboards
join csb in db.CustomerSurfBoards on sb.SurfBoardID equals csb.SurfBoardID
join c in db.Customers on csb.CustomerID equals c.CustomerID
where c.IsActive
group new { sb,csb} by new {sb.ID, csb.ComponentId} into g
select new ReportModel()
{
ReceivedDate = g.First().Name,
Number = c.First().Number <------- this cannot be accessed
}
what I'm trying to achieve is something like this
select sb.Id, max(c.Number), cbs.Id from Surfboards as sb
inner join CustomerSurfBoards as cbs on sb.SurfBoardID = csb.SurfBoardID
inner join Customers as c on csb.CustomerID = c.CustomerID
group by sb.Id, csb.ComponentId
Try this:
var query = from sb in db.Surfboards
join csb in db.CustomerSurfBoards on sb.SurfBoardID equals csb.SurfBoardID
join c in db.Customers on csb.CustomerID equals c.CustomerID
where c.IsActive
select new {sb.id, c.number, cbs.componentid} into tmp
from t in tmp
group t by new {t.ID, t.ComponentId} into g
select new
{
g.Key.id, g.Key.componentid, number = g.Select(n=>n.number).OrderByDescending().FirstOrDefault()
}
Related
I am asking for your help regarding a linq query to SQL.
Here is a part of the diagram of my database: https://imgur.com/xFBUm3q
My problem is in the following relationship: tbl_607_bottle and tbl_607_gaz_reporting, I can have several reportings for a bottle but reporting can only have one bottle.
I do this request but it's not satisfying.
var GazReportingWizardViewModel =
(from gr in db.tbl_607_gaz_reporting
join a in db.tbl_607_actors on gr.FK_ID_actors equals a.id
join bo in db.tbl_607_bottle on gr.FK_ID_bottle equals bo.ID
join loc in db.tbl_607_location on bo.FK_ID_location equals loc.ID
join cc in db.tbl_607_conformity_certificate on bo.FK_ID_conformity_certificate equals cc.ID
join j in db.tbl_607_join_bottle_gaz on bo.ID equals j.FK_ID_bottle
join g in db.tbl_607_gaz on j.FK_ID_gaz equals g.ID
join od in db.tbl_607_order_details on g.FK_ID_order_details equals od.ID
where loc.ID == Process
select new GazReportingWizardViewModel
{
bottle_conti_number = bo.bottle_conti_number,
pressure_value = gr.pressure_value,
reporting_date = gr.reporting_date,
first_name = gr.tbl_607_actors.first_name,
last_name = gr.tbl_607_actors.last_name,
expiration_date = cc.expiration_date,
content = od.content_comments
}).Distinct()
.OrderBy(t => t.reporting_date)
.ToList();
I want the last report on each bottle but it return all reports on each bottle.
Would you have an idea of the solution?
Thank you for your time
Thank you so much!
I persisted in trying to solve the problem in a single query when the solution was so simple.
var GazReportingWizardViewModel = (from gr in db.tbl_607_gaz_reporting
join a in db.tbl_607_actors on gr.FK_ID_actors equals a.id
join bo in db.tbl_607_bottle on gr.FK_ID_bottle equals bo.ID
join loc in db.tbl_607_location on bo.FK_ID_location equals loc.ID
join cc in db.tbl_607_conformity_certificate on bo.FK_ID_conformity_certificate equals cc.ID
join j in db.tbl_607_join_bottle_gaz on bo.ID equals j.FK_ID_bottle
join g in db.tbl_607_gaz on j.FK_ID_gaz equals g.ID
join od in db.tbl_607_order_details on g.FK_ID_order_details equals od.ID
where loc.ID == Process
select new GazReportingWizardViewModel
{
bottle_conti_number = bo.bottle_conti_number,
pressure_value = gr.pressure_value,
reporting_date = gr.reporting_date,
first_name = gr.tbl_607_actors.first_name,
last_name = gr.tbl_607_actors.last_name,
expiration_date = cc.expiration_date,
content = od.content_comments
}).ToList();
var res = from element in GazReportingWizardViewModel
group element by element.bottle_conti_number
into groups
select groups.OrderByDescending(p => p.reporting_date).First();
I need to convert the following complicated sql query to Linq in C#:
Select Empleador.NombreComercial as Empresa,
Vacante.Puesto as Vacante,
Vacante.Actividades,
COUNT(Vacante.CveVacante) as Visitas
from Vacante
LEFT JOIN Empleador on Empleador.CveEmpleador=Vacante.CveEmpleador
LEFT JOIN VisitaVacante on Vacante.CveVacante = VisitaVacante.CveVacante
GROUP BY Empleador.NombreComercial,Vacante.Puesto, Vacante.Actividades,
Vacante.CveVacante HAVING COUNT(*) > 1 ORDER BY Visitas DESC
For the moment I already have the following:
var Visitas = (from tvacante in db.VacanteT
join tEmpleador in db.EmpleadorT on tvacante.CveEmpleador equals tEmpleador.CveEmpleador
join tVisitaVacante in db.VisitaVacanteT on tvacante.CveVacante equals tVisitaVacante.CveVacante
select new
{
Empresa = tEmpleador.NombreComercial,
Vacante = tvacante.Puesto,
tvacante.Actividades,
Visitas = tvacante.CveVacante
}).GroupBy( );
How can I add the COUNT(Vacante.CveVacante) as Visitas and also the
GROUP BY Empleador.NombreComercial,Vacante.Puesto, Vacante.Actividades,
Vacante.CveVacante HAVING COUNT(*) > 1 ORDER BY Visitas DESC
to my linq query? I can't find information about how to complete this. The tables are tvacante, templeador, and tvisitaVacante.
Try this:
var Visitas =(from tvacante in db.VacanteT
join tEmpleador in db.EmpleadorT on tvacante.CveEmpleador equals tEmpleador.CveEmpleador
join tVisitaVacante in db.VisitaVacanteT on tvacante.CveVacante equals tVisitaVacante.CveVacante
group new{tEmpleador.NombreComercial,tvacante.Puesto, tvacante.Actividades} by new {tEmpleador.NombreComercial,tvacante.Puesto, tvacante.Actividades} into g
where g.Count()>1
select new
{
Empresa = g.Key.tEmpleador.NombreComercial,
Vacante = g.Key.tvacante.Puesto,
Actividades= g.Key.tvacante.Actividades,
Visitas = g.Count()
}).OrderByDescending(e=>e.Visitas);
If you want to do it using only linq query syntax and not merging both syntax then you could also do this:
var Visitas = from tvacante in db.VacanteT
join tEmpleador in db.EmpleadorT on tvacante.CveEmpleador equals tEmpleador.CveEmpleador
join tVisitaVacante in db.VisitaVacanteT on tvacante.CveVacante equals tVisitaVacante.CveVacante
group new{tEmpleador.NombreComercial,tvacante.Puesto, tvacante.Actividades} by new {tEmpleador.NombreComercial,tvacante.Puesto, tvacante.Actividades} into g
where g.Count()>1
orderby g.Count() descending
select new
{
Empresa = g.Key.tEmpleador.NombreComercial,
Vacante = g.Key.tvacante.Puesto,
Actividades= g.Key.tvacante.Actividades,
Visitas = g.Count()
};
When I run this Query in SQL I get what I want:
SELECT Auckland_Park.Formative.[Formative Name]
FROM Auckland_Park.LearningUnit
INNER JOIN Auckland_Park.Formative
ON Auckland_Park.LearningUnit.ID = Auckland_Park.Formative.FK_LU
INNER JOIN Auckland_Park.Reference
INNER JOIN Auckland_Park.Course
ON Auckland_Park.Reference.FK_Course = Auckland_Park.Course.ID
ON Auckland_Park.LearningUnit.ID = Auckland_Park.Reference.FK_LU
WHERE Auckland_Park.Course.Name = 'BI'
My result:
Querying SQL Build
Report Develop
Java App Develop
Andriod App Set up
SharePoint Server
But when I work with my C# app I'm using LINQ to SQL, my LINQ Query looks like this:
//LINQ Query to fill Foramtive Name ComboBox
CTUDataContext data = new CTUDataContext();
var course = (from r in data.LearningUnits
join a in data.Formatives
on r.ID equals a.FK_LU
join f in data.References
on r.ID equals f.FK_LU
join g in data.Courses
on f.FK_LU equals g.ID
where g.Name == ("BI")
select new
{
formativeName = a.Formative_Name,
ID = a.ID
}
).ToList();
txtFormativeName.ItemsSource = course;
txtFormativeName.DisplayMemberPath = "formativeName";
txtFormativeName.SelectedValuePath = "ID";
It seems the same, but I'm not getting the same result that I'm getting with the SQL Query above.
//LINQ Query to fill Foramtive Name ComboBox
CTUDataContext data = new CTUDataContext();
var course = (from r in data.LearningUnits
join a in data.Formatives
on r.ID equals a.FK_LU
join f in data.References
on r.ID equals f.FK_LU
join g in data.Courses
on f.FK_LU equals g.ID
where g.Name == ("BI")
select new
{
formativeName = a.Formative_Name,
ID = a.ID
}
).ToList();
txtFormativeName.ItemsSource = course;
txtFormativeName.DisplayMemberPath = "formativeName";
txtFormativeName.SelectedValuePath = "ID";
ANSWER:
on f.FK_LU equals g.ID
f.FK_LU
must be replaced with
f.FK_Course
var query = from r in db.Resource
join c in db.ResourceProjectedCapacity on r.ID equals c.ResourceID into ps
from c in ps.DefaultIfEmpty(null)
join p in db.Project on c.ProjectID equals p.ID
select new
{
Capacity = c,
Resource = r,
Project = p
};
I have this linq query but it is only returning resources that have a matching row on ResourceProjectedCapacity table. How can I get all resources and in case they dont have a matching record the Capacity object to be null?
from i in db.Resource
let c = db.ResourceProjectedCapacity.Where(cc => i.id == cc.ResourceID).FirstOrDefault()
let p = db.Project.Where(pp => c.ProjectID == pp.ID).FirstOrDefault()
select new
{
Capacity = C,
Resource = i,
Project = p
}
try above code
I think the secondary inner join messes up the left outer join above it. I think a way to work around it is to break the join into a seperate query, and then left join on that, something like this:
var subquery = from c in db.ResourceProjectedCapacity
join p in db.Project on c.ProjectID equals p.ID
select new { c, p };
var query = from r in db.Resource
join c in subquery on r.ID equals c.c.ResourceID into ps
from c in ps.DefaultIfEmpty(null)
select new
{
Capacity = c.c,
Resource = r,
Project = c.p
};
NB don't worry, it won't do two db queries, it'll only execute against your db once you evaluate query with a .ToList() or something like that.
I have a join query and i want to filter the result of this query by using distinct. I want to get only one of the shoes which has same brand, model, primary color and secondary color. How can i make this ? Here is my join query.
var query = from b in db.BrandTbls.AsQueryable()
join m in db.ShoeModelTbls on b.BrandID equals m.BrandID
join s in db.ShoeTbls on m.ModelID equals s.ModelID
join i in db.ShoeImageTbls on s.ShoeID equals i.ShoeID
where s.Quantity > 0
orderby m.ModelName
select new
{
s.ShoeID,
m.ModelName,
m.Price,
b.BrandName,
i.ImagePath
};
I found the solution. This query does approximately what i want to do
var query = from b in db.BrandTbls.AsQueryable()
join m in db.ShoeModelTbls on b.BrandID equals m.BrandID
join s in db.ShoeTbls on m.ModelID equals s.ModelID
join i in db.ShoeImageTbls on s.ShoeID equals i.ShoeID
group new {b,m,s,i} by new {b.BrandName,m.ModelName,m.Price,s.ShoeID,s.PrimaryColor,s.SecondaryColor,i.ImagePath} into g
select new {g.Key.ShoeID,g.Key.BrandName,g.Key.ModelName,g.Key.ImagePath,g.Key.Price};
Remove price from the output and use Distinct() like this:
var query = (from b in db.BrandTbls.AsQueryable()
join m in db.ShoeModelTbls on b.BrandID equals m.BrandID
join s in db.ShoeTbls on m.ModelID equals s.ModelID
join i in db.ShoeImageTbls on s.ShoeID equals i.ShoeID
where s.Quantity > 0
orderby m.ModelName
select new
{
s.ShoeID,
m.ModelName,
b.BrandName,
i.ImagePath
}).Distinct();