I have this linq query:
var query = (from dc in context.Table1.Include(d => d.Doc)
join u in _context.Table2 on dc.IDDoc equals u.IDDoc
where dc.ID == id && u.IDUser == user.IDUser
select dc)
.Union(from dc in context.Table1.Include(d => d.Doc)
join p in _context.Table3 on dc.IDDoc equals p.IDDoc
where dc.ID == id
select dc);
And I want to add more where conditions dynamically depends of a list (List ids)
What I want to achieve is something like this:
Imagine that I have a List ids = new(){1, 2, 5, 27);
What I want to do is to add that info into this part of the query to have something like this:
.Union(from dc in context.Table1.Include(d => d.Doc)
join p in _context.Table3 on dc.IDDoc equals p.IDDoc
where dc.ID == id && p.ID == 1 || p.ID == 2 || p.ID == 5 || p.ID = 27
select dc)
But if next time list is List ids = new(){4}, query should look like:
.Union(from dc in context.Table1.Include(d => d.Doc)
join p in _context.Table3 on dc.IDDoc equals p.IDDoc
where dc.ID == id && p.ID == 4
select dc)
Is it even possible? If not, what would be a possible solution?
Thank you
EDIT: I made up with this query because I have no clue about how to add it to my main query.
What I really have is this:
var mainQuery = _context.RootTable
.Include(i => i.Items).ThenInclude(dc => dc.Docs)
.Include(i => i.Items).ThenInclude(sg => sg.Signs)
.FirstOrDefault(m => m.ID== id);
And what I want to do is to filter the ".ThenInclude(dc => dc.Docs) with the other query. I can't figure out how to do it in a better and efficient way that with two sepparate queries.
Use Enumerable.Contains:
List<int> ids = new(){4};
....
.Union(from dc in context.Table1.Include(d => d.Doc)
join p in _context.Table3 on dc.IDDoc equals p.IDDoc
where dc.ID == id && ids.Contains(p.ID) // here
select dc)
....
Related
select t.*
from Task t
inner join Project p on a.ProjectId = t.ProjectId
where p.ProjectTypeId IN ( select ptg.ProjectTypeId
from UserGroup ug
inner join ProjectTypeGroup ptg on ug.GroupId = ptg.GroupId
where ug.UserId = 1 -- MUTABLE VALUE
)
In the attempt query given by you, I don't see Task being used.
Since there is no relation between your sub-query and your main query, you should split them in to two queries:
var projTypeIds = (from ug in UserGroup
join ptg in ProjectTypGroup on ug.GroupId equals ptg.GroupId
where ug.UserId == 1
select ptg.ProjectTypeId).ToList()
Once you have your output, check for .Contains
var task = (from t in Task
join p in Project on p.ProjectId equals t.ProjectId
where projTypeIds.Contains(p.ProjectTypeId)
select t).FirstOrDefault();
I assume you need only one object from this query hence used .FirstOrDefault(), if you are expecting a list using .ToList()
You can use this.
from t in Task
join p in Project
on t.ProjectId equals p.ProjectId
let subQ = ( from ug in UserGroup
join ptg in ProjectTypeGroup
on ug.GroupId equals ptg.GroupId
where ug.UserId == 1
select ptg.ProjectTypeId)
where subQ.Contains(p.ProjectTypeId)
select t
or you can use this.
int loggedUserId = 1;
var _userGroups =
UserGroup.Join(ProjectTypeGroup,
t => t.GroupId, p => p.GroupId,
(t, p) => new {t, p})
.Where(n => n.t.UserId == loggedUserId)
.Select(s => s.p.ProjectTypeId);
var projectTypeIds =
Task.Join(Project,
t => t.ProjectId, p => p.ProjectId,
(t, p) => new {t, p})
.Where(n => _userGroups.Contains(n.p.ProjectTypeId) )
.Select(n => n.t);
projectTypeIds.ToList();
I have join 3 tables using linq query I want to change it to use lambda?
var listOFValue = (from form in db.Forms
join control in db.Controls on form.RecordId equals control.FormId
join values in db.Values on control.RecordId equals values.ControlId
where form.RecordId == formId && control.RecordId == fieldId
orderby values.Name ascending
select values).ToList();
return listOFValue;
Like this :
var listOFValue = (db.Forms.Join(db.Controls, form => form.RecordId, control => control.FormId,
(form, control) => new {form, control})
.Join(db.Values, #t => control.RecordId, values => values.ControlId, (#t, values) => new {#t, values})
.Where(#t => form.RecordId == formId && control.RecordId == fieldId)
.OrderBy(#t => values.Name)
.Select(#t => values)).ToList();
According to this query i get all records which have same id but i want only one time that record
var query = (from c in CompObj.EmpInfoes
join d in CompObj.Leaves on c.EmpID equals d.ProjectManagerID
where c.RoleID == 4 || c.RoleID == 2
select new { c.EmpName, c.EmpID });
var query = (from c in CompObj.EmpInfoes
join d in CompObj.Leaves on c.EmpID equals d.ProjectManagerID
where c.RoleID == 4 || c.RoleID == 2
select new { c.EmpName, c.EmpID })
.Distinct();
Or was there something more you needed?
Just add .Distinct() at the end.
I need to write following query in Linq to SQL but not sure what is the best way of doing, given it has two derived tables. Any suggestions.
SELECT A.ID
FROM
(
SELECT *
FROM Orders
WHERE ProductID = 5
) A
JOIN
(
SELECT CustomerID, MAX(Price) Price
FROM Orders
WHERE ProductID = 5
GROUP BY CustomerID
) B
ON A.CustomerID = B.CustomerID and A.Price = B.Price
var b = (
from o in db.Orders
where o.ProductID == 5
group o by o.CustomerID into og
select new {
CustomerID = og.Key
Price = Max(og.Price)
}
);
var a = (
from o in db.Orders
join p in b on new {a.CustomerID, a.Price} equals
new {b.CustomerID, b.Price}
where o.ProductID == 5
select a.ID
);
var r = a.ToString();
These two links are invaluable when forming things like this:
http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b
http://msdn.microsoft.com/en-us/vstudio/bb688085
Can you simplify this with LINQ, especially if you use method syntax instead of query syntax.
orders.Where(o => o.ProductID == 5)
.GroupBy(o => o.CustomerID)
.SelectMany(g => g.Where(o => o.Price == g.Max(m => m.Price)));
My advice when writing LINQ, do not simply attempt to convert a SQL statement exactly. Think about the desired result and develop a solution designed for LINQ.
Something along these lines:
var result = from a in context.Orders
join b in (context.Orders.Where(o => o.ProductID == 5).GroupBy(o => o.CustomerID).Select(g => new { CustomerID = g.Key, Price = g.Max(o => o.Price)))
on new {a.CustomerID, a.Price} equals new {b.CustomerID, b.Price}
where a.ProductID == 5
select a.ID;
here is my linq code:
BOOK entity = db.BOOKS
.Where(s => s.ID == (from p in db.LIBRARY
from b in db.BOOKS
where (p.ID == 123) && (p.idpage == b.idpage)
select b.fields));
My actual oracle code is:
SELECT DISTINCT BOOKS.ID
FROM LIBRARY,BOOKS
WHERE LIBRARY.ID = 123 AND LIBRARY.ID = BOOKS.ID
But its showing the error in s.ID that..
Delegate 'System.Func Project.Models.BOOKS,int,bool' does not take 1 arguments
Why does this happen? Are there any workarounds?
Your SQL is using a join, so you can do the same thing in LINQ. Either of these approaches will suffice:
// join
var query = (from b in db.BOOKS
join p in db.LIBRARY on b.IdPage equals p.IdPage
where p.ID == 123
select b.Id).Distinct();
// 2 from statements (SelectMany) can also be used as a join
var query = (from b in db.BOOKS
from p in db.LIBRARY
where p.ID == 123 && b.IdPage == p.IdPage
select b.Id).Distinct();
// fluent syntax
var query = db.BOOKS
.Where(b => db.LIBRARY.Any(p =>
p.ID == 123 && b.IdPage == p.IdPage))
.Select(b => b.Id)
.Distinct();
s.ID is comparing to an Enumerable, so you get the error.
At the end of the LINQ query, add a SingleOrDefault().
Your subquery returns a sequence of values, not a single values, so you can't compare it to a scalar property like ID. You should use First on the result of the subquery to get the first result (or Single if there should be only one)
BOOK entity = db.BOOKS
.Where(s => s.ID == (from p in db.LIBRARY
from b in db.BOOKS
where (p.ID == 123) && (p.idpage == b.idpage)
select b.fields).First());
You should be able to use the navigation properties on your BOOKS class to do something like this:
var bookIds = db.BOOKS.Where(b => b.LIBRARIES.Any(l => l.ID == 123))
.Select(b => b.ID)