I have this linqued query
var moreThen1dayLeavefed = (from LApp in db.LeaveApplications
join Emp in db.Employees
on LApp.Employee equals Convert.ToInt32(Emp.EmployeeNumber)
join LBrk in db.LeaveBreakups
on LApp.Id equals LBrk.LeaveApplication
where Emp.Team == 8 && LBrk.StartDate.Year == 2015 && LBrk.StartDate.Month == 5
select new { StartDate = LBrk.StartDate.Day, EndDate = LBrk.EndDate.Day, diff = (DbFunctions.DiffDays(LBrk.StartDate, LBrk.EndDate) + 1) }).ToList();
it gives error
LINQ to Entities does not recognize the method 'Int32 ToInt32(System.String)' method, and this method cannot be translated into a store expression.
on line 3, i.e
on LApp.Employee equals Convert.ToInt32(Emp.EmployeeNumber)
as I am converting the string to int during inner join
Just saw your related question. Your EmployeeNumber field seems to be filled with fixed size (5) zero left padded string representation of a number. If that's true, you can use the trick from how to sort varchar column containing numeric values with linq lambdas to Entity to solve the issue.
Just replace
on LApp.Employee equals Convert.ToInt32(Emp.EmployeeNumber)
with
on DbFunctions.Right("0000" + LApp.Employee.ToString(), 5) equals Emp.EmployeeNumber
Related
I need to count how many records in the tableA are not in the tableA, how to do this with LINQ?
with SQL I do the following way
select count(*) as total from produtoitemgrade g
where g.id not in (select idprodutograde from produtoestoque where idProduto = 12)
and g.idProduto = 12
my linq code so far.
var temp = (from a in Produtoitemgrades
join b in Produtoestoques on a.IdUnico equals b.IdUnicoGrade into g1
where g1.Count(y => y.IdProduto == 12)>0 && !g1.Any()
select a).ToList();
I tried to follow that example LINQ get rows from a table that don't exist in another table when using group by?
but an error occurs when running, how can I do this?
Thanks!
Your query should looks like the following, if you want to have the same SQL execution plan:
var query =
from a in Produtoitemgrades
where !Produtoestoques.Where(b => a.IdUnico == b.IdUnicoGrade && b.idProduto == 12).Any()
&& a.idProduto == 12
select a;
var result = query.Count();
Is it possible to do orderby expression using linq query expression based on dynamic string parameter? because the query i have is producing weird SQL query
my linq:
var product = from prod in _context.Products
join cat in _context.Categories on prod.CategoryId equals cat.CategoryId
join sup in _context.Suppliers on prod.SupplierId equals sup.SupplierId
orderby sortParam
select new ProductViewModel
{
ProductName = prod.ProductName,
ProductId = prod.ProductId,
QuantityPerUnit = prod.QuantityPerUnit,
ReorderLevel = prod.ReorderLevel,
UnitsOnOrder = prod.UnitsOnOrder,
UnitPrice = prod.UnitPrice,
UnitsInStock = prod.UnitsInStock,
Discontinued = prod.Discontinued,
Category = cat.CategoryName,
Supplier = sup.CompanyName,
CategoryId = cat.CategoryId,
SupplierId = sup.SupplierId
};
where var sortParam = "prod.ProductName"
The code above produces weird sql where order by sortParam is being converted to (SELECT 1). Full query catched by sql profiler below:
exec sp_executesql N'SELECT [prod].[ProductName], [prod].[ProductID], [prod].[QuantityPerUnit], [prod].[ReorderLevel], [prod].[UnitsOnOrder], [prod].[UnitPrice], [prod].[UnitsInStock], [prod].[Discontinued], [cat].[CategoryName] AS [Category], [sup].[CompanyName] AS [Supplier], [cat].[CategoryID], [sup].[SupplierID]
FROM [Products] AS [prod]
INNER JOIN [Categories] AS [cat] ON [prod].[CategoryID] = [cat].[CategoryID]
INNER JOIN [Suppliers] AS [sup] ON [prod].[SupplierID] = [sup].[SupplierID]
ORDER BY (SELECT 1)
OFFSET #__p_1 ROWS FETCH NEXT #__p_2 ROWS ONLY',N'#__p_1 int,#__p_2 int',#__p_1=0,#__p_2=10
I'm seeing a lot of people doing linq order by using dynamic parameter but all of them use lambda not query expression, please enlighten me
As was already mentioned, you are passing a string value instead of an expression that reflects the column name. There are options for what you want however, see for example here.
I have a database table with two columns: StartDateTime and FinishDateTime. both are nullable datetime columns.
I'm wanting to calculate the Average time between both fields per row. ie the average duration of my recorded event.
I'm getting a "DbArithmeticExpression arguments must have a numeric common type."
Example EF code with a touch of simplification for the demo.
from p in new DbContext()
where p.user_id = 123
&& p.StartDateTime != null
&& p.FinishDateTime != null
select new {p.StartDateTime, p.FinishDateTime})
.Average(p=> (p.FinishDateTime.Value - p.StartDateTime.Value).Ticks)
I'd love an example of the above, as SQL makes this a breeze.
Its depends on your data provider, it may support DbFunctions and you could do something like this:
(from p in new DbContext()
where p.user_id = 123
&& p.StartDateTime != null
&& p.FinishDateTime != null
select new {p.StartDateTime, p.FinishDateTime})
.Average(x=> DbFunctions.DiffMilliseconds(p.FinishDateTime,p.StartDateTime))
if it doesn't, i think you have to go linq to objects after the select:
(from p in new DbContext()
where p.user_id = 123
&& p.StartDateTime != null
&& p.FinishDateTime != null
select new {p.StartDateTime, p.FinishDateTime})
.ToArray()
.Average(x=> (p.FinishDateTime -p.StartDateTime).Ticks)
I`m using Entity Framwork and i have the next projection:
var items = from mapsDsc in DbContext.MapsDesc
join mapCat in DbContext.MapsCategories on mapsDsc.MapID equals mapCat.MapID
join mainCat in DbContext.MainCategories on mapCat.MainCategory equals mainCat.MainCatID
join subCat in DbContext.SubCategories on mapCat.SubCategory equals subCat.SubCatID
select new DataModel.ComplexEntities.MapsDescExt
{
MapID = mapsDsc.MapID,
MapName = mapsDsc.MapName,
MapLink = mapsDsc.MapLink,
Note = mapsDsc.Note,
MainCategoryID = mapCat.MainCategory,
MainCategoryName = mainCat.Category,
SubCategoryID = mapCat.SubCategory,
SubCategoryName = subCat.Category
};
Please notice that this projection filling strong type and not anonymous one.
I need to customize this projection a little bit but i don`t know how.
At my last join i need to implement the next condition with "or" operator:
join subCat in DbContext.SubCategories on mapCat.SubCategory equals subCat.SubCatID or subCat.SubCatID equals "0"
How can I do it? All the exampels I seen relate to anonymous types and it`s not good for me.
Thanks
You don't have to use the join syntax, you can do the same by a manual where and then slip in an extra condition:
var items = from mapsDsc in DbContext.MapsDesc
join mapCat in DbContext.MapsCategories on mapsDsc.MapID
equals mapCat.MapID
join mainCat in DbContext.MainCategories on mapCat.MainCategory
equals mainCat.MainCatID
from subCat in DbContext.SubCategories
/* here */ where mapCat.SubCategory == subCat.SubCatID || subCat.SubCatID == "0"
select new DataModel.ComplexEntities.MapsDescExt
{
...
(Note that mapCat.SubCategory should be an id field, you probably know which).
I have a problem with a creation of a Linq to Entities (Oracle 11g) request. Here is the
I have a table TREATMENT with three column (simplified version) : ID, STATE and APPLICATION. Here is a sample :
ID STATE APPLICATION
1 A MAJ
2 A FLUX
3 A FLUX
4 R REF
5 A REF
Now, my objectives are to retrieve the data with theses rules:
State must be A (added)
Number of rows per application below a max value
The max value is minored b the number of row with State = R (per application)
Exemple : If the max value is 1, I must retrieve row 1 and 2. (Can't retrieve row 5 since there is already a REF with state R (the row 4))
I manage to retrieve all the row when the number of R is equal or greater than the max value, but I don't see how to limit my number of result in order to respect the max value.
Here is the request :
using (Entities bdd = new Entities())
{
var treatments = from trt in bdd.TREATMENT
let app = from t in bdd.TREATMENT
where t.STATE == "R"
group t by t.APPLICATION into grouped
where grouped.Count() >= maxPerApplication
select grouped.Key
where trt.STATE == "A" && !app.Contains(trt.APPLICATION)
orderby trt.ID
select new TreatmentDto()
{
Id = trt.ID
};
result = treatments.ToList();
}
In SQL, I would use an inner request and a ROWNUM to limit the number of result, but I don't see how to do it. The only solution I see is to do the request in two parts, but I want to avoid this to maintain the consistency of the information.
I found a solution, not sure if it's the best, but it works :
using (Entities bdd = new Entities())
{
from trt in bdd.TREATMENT
where trt.STATE == "A" &&
(from trt2 in bdd.TREATMENT
where trt2.STATE == "A" && trt2.APPLICATION == trt.APPLICATION && trt2.ID <= trt.ID
select trt2).Count() <= maxPerApplication - (from appp in bdd.TREATMENT
where appp.STATE == "R"
&& appp.APPLICATION.Equals(trt.APPLICATION)
select appp).Count()
select new TreatmentDto()
{
Id = trt.ID
};
result = treatments.ToList();
}