I'm wondered I have a table with IDs and a version and a remove field. I d like to return the the top 20 records grouped by ID and for ech ID take only the highest version unless remove is set then ignore removed records.
Then return a descending record set.
There are a few ways todo it with Linq but I wonder is there a most efficient way, are there patterns to avoid?.
...
.OrderByDescending(x=>x.id)
.GroupBy(x=>x.id)
.SelectMany(y=>y.Where(x=>x.Version == y.Max(y=>y.Version)))
.Where(x=>x.Remove=false)
.Take(20)
One of then possible workarounds when using EF Core. I'm calling it workaround because with SQL and Window functions we can create more effective query.
var itemsQuery = ctx.SomeTable
.Where(x => x.Remove = false);
var query =
from d in itemsQuery.Select(d => new { d.id }).Distinct()
from x in itemsQuery.Where(x => d.Id == x.Id)
.OrderByDescending(x => x.Version)
.Take(1)
select x;
query = query.Take(20);
Similar queries when using EF Core 6:
var query = ctx.SomeTable
.Where(x => x.Remove = false)
.GroupBy(x => x.Id)
.Take(20)
.SelectMany(g => g.OrderByDescending(x => x.Version).Take(1));
var query = ctx.SomeTable
.Where(x => x.Remove = false)
.GroupBy(x => x.Id)
.Select(g => g.OrderByDescending(x => x.Version).First());
.Take(20);
Related
I have a table with 3 columns.
And I would like to present a table with this structure:
Can someone show me how to do this with Lambda expressions?
So far I've only gotten the result if I only wanted to show one column:
var sum_data = _context.HechosFinanza
.Where(x => x.Product.Sale_Type == "Cash Sale")
.GroupBy(x => x.Product.Product_Name)
.Select(x => Product { Tienda = x.Key, Total = x.Sum(s =>
s.sales_amount) });
I don't know if something like this may be possible (no idea really, just trying to figure it out):
var sum_data = _context.HechosFinanza
// I remove there where condition from here
.GroupBy(x => x.Product.Product_Name)
// And I add the where condition in each sum
.Select(x => Product { Tienda = x.Key,
TotalCash = x.Sum(s => s.sales_amount).Where(s => s.Product.Sale_Type == "Cash Sale"),
TotalCredit = x.Sum(s => s.sales_amount).Where(s.Product.Sale_Type == "Credit Sale")
});
Uhm, well. It turns out I was really close.
Just had to put the 'Where' statement before.
Answer:
var sum_data = _context.HechosFinanza
// I remove there where condition from here
.GroupBy(x => x.Product.Product_Name)
// And I add the where condition in each sum
.Select(x => Product { Tienda = x.Key,
TotalCash = x.Where(s => s.Product.Sale_Type == "Cash Sale").Sum(s => s.sales_amount),
TotalCredit = x.Where(s.Product.Sale_Type == "Credit Sale") .Sum(s => s.sales_amount)
});
And done.
I have a simple table which only has 3 columns { id, DateTime, NumberOfCoils }, I need to get the results of the query grouped together by the DateTime with the sum of the NumberOfCoils on that particular date.
return testData.MOCK_DATA.Select(x => new { x.NumberOfCoils, x.DateTime })
.AsEnumerable()
.Where(x => x.DateTime> DateTime.Now.AddDays(-numberOfDays))
.Select(x => new { formattedDate = x.DateTime.ToString("yyyy-MM-dd"), x.NumberOfCoils })
.OrderBy(x => x.formattedDate)
.ToList();
I've looked for solutions here but I couldn't figure out how to solve it. I think that part of what's making it hard for me to find a solution is because I have to do some formatting as well.
I'm pretty new to using EF so I apologize if this is a bad question.
Try this:
return testData.MOCK_DATA.Select(x => new { x.NumberOfCoils, x.DateTime })
.AsEnumerable()
.Where(x => x.DateTime> DateTime.Now.AddDays(-numberOfDays))
.GroupBy(x => x.DateTime)
.Sum(x => x.NumberOfCoils);
You need to actually use GroupBy:
return testData.MOCK_DATA.Where(x => x.DateTime > DateTime.Now.AddDays(-numberOfDays))
.GroupBy(d => d.DateTime)
.Select(dg => new { formattedDate = dg.Key.ToString("yyyy-MM-dd"), NumberOfCoils = dg.Sum(d => d.NumberOfCoils) })
.OrderBy(x => x.formattedDate)
.ToList();
I have table structure like
Product {List<Cost> Costs}
Cost{List<Invoice> Invoices, Product product}
Invoice{bool isIncluded}
Need a query to get all Products which has any Cost for which none of invoice is included (isIncluded=false for all)
I tried something like:
Product pro= null;
Product p = null;
var costQuery = QueryOver.Of<Cost>()
.JoinAlias(c => c.Product, () => p)
.Where(() => p.Id == pro.Id)
.WhereNot(c=>c.Invoices.Any(i=>i.IsIncluded))
.Select(c => c.Id);
var query = CurrentSession.QueryOver<Product>(() => pro)
.WithSubquery.WhereExists(costQuery);
Use of 'Any' in query errors out:
Unrecognised method call: System.Linq.Enumerable:Boolean
Any[Invoice](System.Collections.Generic.IEnumerable1[Trigger.StageGate.Services.BusinessEntities.Invoice],
System.Func2[Trigger.StageGate.Services.BusinessEntities.Invoice,System.Boolean])
try:
var costQuery = QueryOver.Of<Cost>()
.JoinAlias(c => c.Product, () => p)
.Where(() => p.Id == pro.Id)
.JoinQueryOver<Invoice>(c => c.Invoices)
.WhereNot(i => i.IsIncluded)
.Select(c => c.Id);
I have the following code:
var statements = db.statement
.OrderByDescending(d => d.id)
.Take(5)
.AsEnumerable()
.Select(d => new Statements
{
Accounts = d.statement_entry.AsEnumerable()
.GroupBy(b => b.currency)
.Select(b =>
new Account
{
In = b.Where(l => l.amount > 0).Sum(l => l.amount),
Out = b.Where(l => l.amount < 0).Sum(l => l.amount),
Balance = b.Sum(l => l.amount),
Currency = b.Key
}).OrderBy(b => b.Currency),
UploadedDate = d.uploaded_date,
Id = d.id
})
.ToList();
Is there a way that I could do it without the AsEnumerable()? From what I understand the AsEnumberable will cause a query to take place for each of the statements returned.
Or is there a better way to refactor the code?
You understand wrongly. AsEnumerable will make the query execute on the local (client) machine.
This
statements = db.statement
.OrderByDescending(d => d.id)
.Take(5)
will be executed on the (SQL) server,
the remaining part on the client
Why are you puttin the AsEnumerable? I think the query should work even without (and it would do everything server-side)
The only thing is that after the OrderBy(b => b.Currency) you should put a .ToList() so that the .Select(b => new Account is materialized and cached.
In the code below I'd like to do a sum for OBFY and CFY separately within each grouping in deptGroup. Anyone have any ideas, I've tried a coupla things but can't get it. Thanks!!
var deptGroup = prodCostsTotals.AsQueryable()
.Select(r => dt.Rows.Add(new object[]
{
Convert.ToInt32(r.Field<string>("Proc")),
r.Field<string>("UnitL"),
r.Field<Decimal?>("OBFY"),
r.Field<Decimal?>("CFY")
})).GroupBy(g => g.Field<string>("Proc"));
It seems to me you are overusing DataRows. If you had your data in a nice class, you could write it like this:
data.GroupBy(x => x.Proc)
.Select(g => new
{
Proc = g.Key,
OBFYSum = g.Sum(x => x.OBFY),
CFYSum = g.Sum(x => x.CFY)
})
But if you really want to start with a DataTable and add the intermediate result to another DataTable, you could do it like this:
prodCostsTotals.AsQueryable()
.Select(r => dt.Rows.Add(new object[]
{
Convert.ToInt32(r.Field<string>("Proc")),
r.Field<string>("UnitL"),
r.Field<Decimal?>("OBFY"),
r.Field<Decimal?>("CFY")
}))
.GroupBy(g => g.Field<string>("Proc"))
.Select(g => new
{
Proc = g.Key,
OBFYSum = g.Sum(x => x.Field<Decimal?>("OBFY")),
CFYSum = g.Sum(x => x.Field<Decimal?>("CFY"))
})
Note that I have no idea whether your use of AsQueryable() will have any effect on the first part of this query, but it certainly won't have any effect on the grouping.