I have the following LINQ query:
var query =
(from p in obj1
group p by p.objID into g
let totalSum = g.Sum(p => p.ObjPrice)
select new { MyObjectID = g.Key, totalSum })
.Max(g => g.totalSum);
I want to select both the object id and price of the object with the maximum price. How can I do that?
Use an order by descending clause and call FirstOrDefault().
(from p in obj1
group p by p.objID into g
let totalSum = g.Sum(p => p.ObjPrice)
orderby totalSum descending
select new { MyObjectID = g.Key, totalSum }).FirstOrDefault();
Related
I have some linq which returns a list of properties and the number of bookings for a given year. However if a property has no bookings then it is not included in the resultset.
var bookings = from b in db.Bookings
orderby b.PropertyId
where b.StartDate.Year == Year
group b by b.Property.Title into grp
select new { key = grp.Key, cnt = grp.Count() };
How can this be changed to include properties with no bookings?
I'm assuming there's a Properties table based on your code. You need to select from Properties instead:
var bookings = from p in db. Properties
orderby p.Id
group p by p.Title into grp
select new
{
key = grp.Key,
cnt = grp.Count(p => p.Bookings.Where(b => b.StartDate.Year == Year))
};
I guess you should filter on year in the count, then
var bookings = from b in db.Bookings
orderby b.PropertyId
group b by b.Property.Title into grp
select new {
key = grp.Key,
cnt = grp.Count(x => x.StartDate.Year == Year)
};
I have the following linq query
var temp = (from p in db.BEM_EVT_FULL
where (p.date_reception > dt)
group p by p.mc_object into g
orderby g.Count() descending
select new StringIntType
{
str = g.Key,
nbr = g.Count()
}).Take(50).ToList();
Instead of casting result to StringIntType i need to use Dictionary with int and string types.
You could try something like this:
var temp = (from p in db.BEM_EVT_FULL
where (p.date_reception > dt)
group p by p.mc_object into g
orderby g.Count() descending
select new
{
Key = g.Key,
Value = g.Count()
}).Take(50)
.ToDictionary(x=>x.Key, y=>y.Value);
it looks like there may be an answer for this question here: Convert Linq Query Result to Dictionary
basically, instead of ToList use ToDictionary
.ToDictionary( t => t.Key, t => t.Value);
I have this Linq query:
from i in data.Items
join tdi in data.TDItems on i.itemId equals tdi.itemId
group i by i.ItemId
into selection
select new
{
itemId = selection.Key
number = selection.Sum(x => x.quantity) // quantity is a field in TDItems
}
How do I create this sum function? because I'm grouping by an attribute in the Items table, I can't call a Sum on the TDItems table.
group new { i, tdi } by i.ItemId
...
select new
{
selection.Sum(x => x.tdi.quantity)
}
from c in (from i in #as
join tdi in bs on i.itemId equals tdi.itemId
select new
{
itemId = i.itemId,
quantity = tdi.quantity
})
group c by c.itemId
into selection
select new
{
itemId = selection.Key,
number = selection.Sum(x => x.quantity) // quantity is a field in TDItems
};
I have the following sql, which I want to convert to linq
SELECT Contrato.finca, SUM(Pago.Importe_subtotal)
FROM Pago, Contrato
WHERE Pago.Contrato = Contrato.ID AND Pago.pagado = 1
GROUP BY Contrato.finca
ORDER BY 2 DESC
GO
What I have now in linq is the following, but the group by doesn't work.
var x = from contrato in ctx.Contratos
join pago in ctx.Pagos
on contrato.ID equals pago.Contrato
where pago.pagado == true
group contrato by contrato.finca
select contrato.Finca1;
Think this should work:
ctx.Pagos.Where(m=>m.pagado==true).GroupBy(m=>m.Contrato.finca)
.Select(m=> new { Id= m.Key, Val= m.Sum(n => n.Importe_subtotal)})
Try
var x = from contrato in ctx.Contratos
join pago in ctx.Pagos
on contrato.ID equals pago.Contrato
where pago.pagado == true
group new {contrato, pago} by contrato.finca into g
select new {
key = g.Key,
sum = g.Sum(p => p.pago.Importe_subtotal)
};
I have some SQL and am trying to make the equivalent in LINQ. This is the SQL:
SELECT Categories.CategoryDescription, Categories.CategoryType AS Type,
Categories.Category, COUNT(CategoryLinks.OrgID) AS CountOfOrgs
FROM CategoryLinks
INNER JOIN Categories ON Categories.CategoryID = CategoryLinks.CategoryID
GROUP BY Categories.Category, Categories.CategoryType, Categories.CategoryDescription
ORDER BY CategoryDescription ASC
Essentially, I want a list of everything from the Categories table and a count of the number of OrgId's in the CategoryLinks table that links to it.
Below is the query I am performing at the moment. There has to be a more efficient way to do this. Am I wrong?
var cnts = (from c in db.Categories
join cl in db.CategoryLinks on c.CategoryID equals cl.CategoryID
group new { c, cl } by new
{
c.CategoryID
} into g
select new
{
CategoryID = g.Key.CategoryID,
categoryCount = g.Count()
});
var results = (from c in db.Categories
join cn in cnts on c.CategoryID equals cn.CategoryID
select new
{
c.CategoryID,
c.CategoryDescription,
c.CategoryType,
Category = c.Category1,
cn.categoryCount
});
I think you want to use the GroupJoin method:
Categories.GroupJoin(
CategoryLinks,
x => x.CategoryID,
y => y.CategoryID,
(x,y) => new{
x.CategoryID,
x.CategoryDescription,
x.CategoryType,
Category = x.Category1,
CategoryCount = y.Count() })
In query syntax, this is written as join..into:
from c in db.Categories
join cl in db.CategoryLinks on c.CategoryID equals cl.CategoryID into catGroup
select new
{
c.CategoryID,
c.CategoryDescription,
c.CategoryType,
Category = c.Category1,
CategoryCount = catGroup.Count()
}
Try this:
var bbb = categories.Join(categoryLinks, c => c.CategoryID, cl => cl.CategoryId, (c, cl) => new {c, cl})
.GroupBy(g => g.c)
.Select(g => new {count = g.Count(), Category = g.Key});
It returns count and all data that is in Category. We group by all columns in category and place result in new anonymous type variable that contains 2 properties: Count, that contains count and Category that is of type Category and contains all data that is in category row.
If you want, you can rewrite it as:
var bbb = categories.Join(categoryLinks, c => c.CategoryID, cl => cl.CategoryId, (c, cl) => new {c, cl})
.GroupBy(g => g.c)
.Select(g => new
{
CategoryID = g.Key.CategoryId,
CategoryDescription = g.Key.CategoryDescription,
CategoryType = g.Key.CategoryType,
Category = g.Key.Category1,
categoryCount = g.Count()
});