Count and Groupby using linq from sql query - c#

Im trying to create a table that counts all orders and groups them in a table from sql to linq to use in a bar graph with google charts.
Table`
Orders Status
8 Created
3 Delayed
4 Enroute
sql
SELECT Count (OrderID) as 'Orders', order_status FROM [ORDER]
where order_status ='Created'OR order_status= 'Delayed' OR order_status='Enroute'
group by order_status
controller
public ActionResult GetChart()
{
var Orders = db.Order.Select(a => new { a.OrderID, a.order_status })
.GroupBy(a => a.order_status);
return Json(Orders, JsonRequestBehavior.AllowGet);
}
this is not displaying the correct results as the linq seems to be wrong.
can someone please point me in the right direction? I am relatively new to this.
thanks in advance.


This should work:-
var result = db.Order.Where(x => x.order_status == "Created"
|| x.order_status == "Delayed"
|| x.order_status == "Enroute")
.GroupBy(x => x.order_status)
.Select(x => new
{
order_status = x.Key,
Orders = x.Count()
});
Or if you prefer query syntax then:-
var result = from o in db.Order
where o.order_status == "Created" || o.order_status == "Delayed"
|| o.order_status == "Enroute"
group o by o.order_status
select new
{
orderStatus = x.Key,
Counts = x.Count()
};


I think you want to group by Status and count total number of orders in each group (I build a simple console program to demonstrate). I suppose the data is:
Orders Status
8 Created
3 Delayed
4 Enroute
2 Created
1 Delayed
Order.cs
public class Order
{
public Order(int orderId, string status)
{
OrderId = orderId;
Status = status;
}
public int OrderId { get; set; }
public string Status { get; set; }
}
Program.cs
class Program
{
static void Main(string[] args)
{
// Data
var orders = new List<Order>
{
new Order(8, "Created"),
new Order(3, "Delayed"),
new Order(4, "Enroute"),
new Order(2, "Created"),
new Order(1, "Delayed"),
};
// Query
var query = orders
.GroupBy(x => x.Status)
.Select(x => new {Status = x.Key, Total = x.Count()});
// Display
foreach (var item in query)
{
Console.WriteLine(item.Status + ": " + item.Total);
}
Console.ReadLine();
}
}
The one you need to focus in is query. After using GroupBy, you will have a list of groups. For each group, the Key is the criteria to group (here is the Status). Then, we call Count() to get the total number of element in that group.
So, from the program above, the output should be:
Created: 2
Delayed: 2
Enroute: 1

Related

EF core query group by date and subquery

I have the following table:
CREATE TABLE "OrderStatusLogs" (
"Id" UNIQUEIDENTIFIER NOT NULL,
"OrderId" UNIQUEIDENTIFIER NOT NULL,
"Status" INT NOT NULL,
"StartDateTime" DATETIMEOFFSET NOT NULL,
"EndDateTime" DATETIMEOFFSET NULL DEFAULT NULL,
PRIMARY KEY ("Id"),
FOREIGN KEY INDEX "FK_OrderStatusLogs_Orders_OrderId" ("OrderId"),
CONSTRAINT "FK_OrderStatusLogs_Orders_OrderId" FOREIGN KEY ("OrderId") REFERENCES "Orders" ("Id") ON UPDATE NO_ACTION ON DELETE CASCADE
)
;
For the following entity:
[DebuggerDisplay(nameof(OrderStatusLog) + " {Status} {StartDateTime} - {EndDateTime}" )]
public class OrderStatusLog
{
public Guid Id { get; set; }
public Guid OrderId { get; set; }
public OrderStatus Status { get; set; }
public DateTimeOffset StartDateTime { get; set; }
public DateTimeOffset? EndDateTime { get; set; }
}
public enum OrderStatus
{
Unknown = 0,
Pending = 1,
Processing = 2,
Shipping = 3,
}
And i'm trying to generate a report which should show how many orders are set to a certain state for a given range.
For example, for the month oktober, we'd have the range 1 to 31 oktober.
The desired output would be something like this:
1/10/2021 Pending 21 orders
1/10/2021 Processing 23 orders
1/10/2021 Shipping 33 orders
1/10/2021 Unknown 0 orders
...
31/10/2021 Pending 1 orders
31/10/2021 Processing 3 orders
31/10/2021 Shipping 44 orders
31/10/2021 Unknown 5 orders
I'm having some difficulties writing a query in EF that would give me the right output. I can get things to work, but only client-side. I'm trying to make this work in the database instead.
So far i tried:
var logsByDayAndOrderId = orderStatusLogs.GroupBy(c => new { c.StartDateTime.Date, c.OrderId }, (key, values) => new
{
key.Date,
key.OrderId,
MaxStartDateTime = values.Max(x => x.StartDateTime)
});
var list = logsByDayAndOrderId.ToList();
var statusByDayAndOrderId = logsByDayAndOrderId.Select(c => new
{
c.Date,
c.OrderId,
orderStatusLogs.FirstOrDefault(x => x.StartDateTime == c.MaxStartDateTime && x.OrderId == c.OrderId).Status
});
//var statusByDayAndOrderId = logsByDayAndOrderId.Join(orderStatusLogs.def, inner => new { inner.OrderId, StartDateTime = inner.MaxStartDateTime }, outer => new { outer.OrderId, outer.StartDateTime }, (inner,outer) => new
//{
// inner.Date,
// inner.OrderId,
// outer.Status
//}); // TODO rem this query gives more results because of the join. we need an Outer join - but i could not get that to work. the version with select above works better, but then it does not use join so it may be slow(er).
var list1 = statusByDayAndOrderId.ToList();
var groupBy = statusByDayAndOrderId
.GroupBy(c => new { c.Date, c.Status })
.Select(c => new { c.Key.Date, c.Key.Status, Count = c.Count() });
var list2 = groupBy.ToList();
Another attempt:
var datesAndOrders = orderStatusLogs
.GroupBy(c => new { c.StartDateTime.Date, c.OrderId }, (key, values) => key);
var ordersByDateAndActiveStatusLog = orderStatusLogs
.Select(c => new
{
c.StartDateTime.Date,
c.OrderId,
ActiveStatusForDate = orderStatusLogs
.OrderByDescending(x => x.StartDateTime)
.FirstOrDefault(x => x.OrderId == c.OrderId && x.StartDateTime.Date == c.StartDateTime.Date)
.Status
});
var list = ordersByDateAndActiveStatusLog.ToList();
var orderCountByDateAndStatus = ordersByDateAndActiveStatusLog
.GroupBy(c => new { c.Date, c.ActiveStatusForDate }, (key, values) => new
{
key, count = values.Count()
});
var list1 = orderCountByDateAndStatus.ToList();
Both of these fail because of Cannot use an aggregate or a subquery in an expression used for the group by list of a GROUP BY clause..
This makes sense.
I'm hoping for someone that could help write a Linq query that generates the right data using ef core.
Notes:
I Solely use the fluent query syntax
I Have more places where i'd like to get data for each day so any other info or tips and tricks are welcome
I use net core 5 with ef core 5.0.11 with a MSSQL database

I would suggest to use EF Core extension linq2db.EntityFrameworkCore which has ability to work with local (in-memory) collections in database queries. Disclaimer: i'm one of the creators.
At first define function which generates days sequence:
public static IEnumerable<DateTime> GenerateDays(int year, int month)
{
var start = new DateTime(year, month, 1);
var endDate = start.AddMonths(1);
while (start < endDate)
{
yield return start;
start = start.AddDays(1);
}
}
Then we can use generated sequence in LINQ Query:
var days = GenerateDays(2021, 10).ToArray();
using var dc = ctx.CreateLinqToDbConnection();
var totalsQuery =
from d in days.AsQueryable(dc)
from l in orderStatusLogs.Where(l =>
(l.EndDateTime == null || l.EndDateTime >= d) && l.StartDateTime < d.AddDays(1))
.DefaultIfEmpty()
group l by new { Date = d, l.Status } into g
into g
select new
{
g.Key.Date,
g.Key.Status,
Count = g.Sum(x => x == null ? 0 : 1),
};
var result = totalsQuery.ToList();
The following SQL should be generated:
SELECT
[d].[item],
[e].[Status],
Sum(IIF([e].[OrderID] IS NULL, 0, 1))
FROM
(VALUES
('2021-05-01T00:00:00'), ('2021-05-02T00:00:00'),
('2021-05-03T00:00:00'), ('2021-05-04T00:00:00'),
('2021-05-05T00:00:00'), ('2021-05-06T00:00:00'),
('2021-05-07T00:00:00'), ('2021-05-08T00:00:00'),
('2021-05-09T00:00:00'), ('2021-05-10T00:00:00'),
('2021-05-11T00:00:00'), ('2021-05-12T00:00:00'),
('2021-05-13T00:00:00'), ('2021-05-14T00:00:00'),
('2021-05-15T00:00:00'), ('2021-05-16T00:00:00'),
('2021-05-17T00:00:00'), ('2021-05-18T00:00:00'),
('2021-05-19T00:00:00'), ('2021-05-20T00:00:00'),
('2021-05-21T00:00:00'), ('2021-05-22T00:00:00'),
('2021-05-23T00:00:00'), ('2021-05-24T00:00:00'),
('2021-05-25T00:00:00'), ('2021-05-26T00:00:00'),
('2021-05-27T00:00:00'), ('2021-05-28T00:00:00'),
('2021-05-29T00:00:00'), ('2021-05-30T00:00:00'),
('2021-05-31T00:00:00')
) [d]([item])
LEFT JOIN [OrderStatusLogs] [e] ON ([e].[EndDateTime] IS NULL OR [e].[EndDateTime] >= [d].[item]) AND [e].[StartDateTime] < DateAdd(day, 1, [d].[item])
GROUP BY
[d].[item],
[e].[Status]

How do I minimize C#, LINQ code in Deleting Multiple Records

Here is a method to delete zero Inventory records from Inventory Table. I would like to reduce code/no of times that LINQ executes on Database.
Inventory Table
public class Inventory
{
public int itemCode { get; set; }
public decimal price { get; set; }
public decimal availQty { get; set; } // Can have Negative values.
}
example data
itemCode price availQty
1 10 10
1 12 -10
2 10 10
From above records, i want to delete all records of itemCode == 1, as net availQty is 0.
Here is my method
private void RemoveZeroInvs()
{
// Remove individual zero Inventorys
var rinvs = from ri in _context.Inventorys
where ri.availQty == 0
select ri;
_context.Inventorys.RemoveRange(rinvs);
_context.SaveChanges();
// Remove if group is zero in availQty, as it allows Negative Qty.
var result = from d in _context.Inventorys
group d by new
{
d.itemCode
}
into g
select new
{
g.Key.itemCode,
availQty = g.Sum(y => y.availQty)
};
var zrs = from r in result
where r.availQty == 0
select r;
foreach (var zr in zrs) // Here, zrs length may be more than 500
{
var ri = _context.Inventorys.Where(w => w.itemCode == zr.itemCode);
_context.Inventorys.RemoveRange(ri);
_context.SaveChanges();
}
}
I use Asp.Net Core 2.2. Is there any such possibility?
Also I get following error at line _context.Inventorys.RemoveRange(ri); in the loop.
A command is already in progress: SELECT t."itemCode", t."availQty"
FROM (
SELECT d."itemCode", SUM(d."availQty") AS "availQty"
FROM "Inventorys" AS d
GROUP BY d."itemCode"
) AS t

var todelete = _context.Inventorys
.GroupBy(i => i.itemCode)
.Where(g => g.Sum(i => i.availQty) == 0)
.SelectMany(g => g);
Here is a shorter versions of your code, in terms of DB excecution, one would have to compare the raw queries. But it may be lighter that your code…

Get data by filtering and grouping LINQ query

Could someone help me to write a code to get data from grouped and filtered query?
Data are from simple datatable, and what I need is how to solve a problem if user enter only one of search param, but also have a possibility to enter more param?
public class Journal
{
public int ID {get; set;}
public string Field1 { get; set; }
public string Field2 { get; set; }
}
/*variables entered bu user:
searchParam1
searchParam2
...
searchParamN
*/
using (var dbContext = new databaseContext())
{
var serchresult = dbContext.Journals
.Where(p => p.Field1.StartsWith(SearchParam1) &&
p.Field2.StartsWith(SearchPParam2))
.GroupBy(f => f.ID)
.ToList();
}
To get filtered data I'v tried:
result = from tr in dbContext.Journals select tr;
if (!String.IsNullOrEmpty(SearchParam1)) {
result = result.Where(tr => tr.Field1.StartsWith(SearchParam1));
}
if (!String.IsNullOrEmpty(SearchParam2)) {
result = result.Where(tr => tr.Field2.StartsWith(SearchParam2));
}
But I need to add grouping :(

You are almost there. Split your query in two parts. In the first part do the dynamic filtering and in the second part do the rest.
var source = dbContext.Journals.AsQueryble();
if (!string.IsNullOrEmpty(SearchParam1))
source = source.Where(tr => tr.Field1.StartsWith(SearchParam1));
if (!string.IsNullOrEmpty(SearchParam2))
source = source.Where(tr => tr.Field2.StartsWith(SearchParam2));
var serchresult = source
.GroupBy(f => f.ID)
.ToList();

You could simplify like this.
result = dbContext.Journals.ToList();
result.Where(tr => ((!String.IsNullOrEmpty(SearchParam1) && tr.Field1.StartsWith(SearchParam1))
|| ( !String.IsNullOrEmpty(SearchParam2) && tr.Field2.StartsWith(SearchParam2)))
.GroupBy(f => f.ID)
.SelectMany(g => g.Select(x=> new { ID = g.Key.ID, x.Field1, x.Field2 }))
.ToList();

How do I get total Qty using one linq query?

I have two linq queries, one to get confirmedQty and another one is to get unconfirmedQty.
There is a condition for getting unconfirmedQty. It should be average instead of sum.
result = Sum(confirmedQty) + Avg(unconfirmedQty)
Is there any way to just write one query and get the desired result instead of writing two separate queries?
My Code
class Program
{
static void Main(string[] args)
{
List<Item> items = new List<Item>(new Item[]
{
new Item{ Qty = 100, IsConfirmed=true },
new Item{ Qty = 40, IsConfirmed=false },
new Item{ Qty = 40, IsConfirmed=false },
new Item{ Qty = 40, IsConfirmed=false },
});
int confirmedQty = Convert.ToInt32(items.Where(o => o.IsConfirmed == true).Sum(u => u.Qty));
int unconfirmedQty = Convert.ToInt32(items.Where(o => o.IsConfirmed != true).Average(u => u.Qty));
//Output => Total : 140
Console.WriteLine("Total : " + (confirmedQty + unconfirmedQty));
Console.Read();
}
public class Item
{
public int Qty { get; set; }
public bool IsConfirmed { get; set; }
}
}

Actually accepted answer enumerates your items collection 2N + 1 times and it adds unnecessary complexity to your original solution. If I'd met this piece of code
(from t in items
let confirmedQty = items.Where(o => o.IsConfirmed == true).Sum(u => u.Qty)
let unconfirmedQty = items.Where(o => o.IsConfirmed != true).Average(u => u.Qty)
let total = confirmedQty + unconfirmedQty
select new { tl = total }).FirstOrDefault();
it would take some time to understand what type of data you are projecting items to. Yes, this query is a strange projection. It creates SelectIterator to project each item of sequence, then it create some range variables, which involves iterating items twice, and finally it selects first projected item. Basically you have wrapped your original queries into additional useless query:
items.Select(i => {
var confirmedQty = items.Where(o => o.IsConfirmed).Sum(u => u.Qty);
var unconfirmedQty = items.Where(o => !o.IsConfirmed).Average(u => u.Qty);
var total = confirmedQty + unconfirmedQty;
return new { tl = total };
}).FirstOrDefault();
Intent is hidden deeply in code and you still have same two nested queries. What you can do here? You can simplify your two queries, make them more readable and show your intent clearly:
int confirmedTotal = items.Where(i => i.IsConfirmed).Sum(i => i.Qty);
// NOTE: Average will throw exception if there is no unconfirmed items!
double unconfirmedAverage = items.Where(i => !i.IsConfirmed).Average(i => i.Qty);
int total = confirmedTotal + (int)unconfirmedAverage;
If performance is more important than readability, then you can calculate total in single query (moved to extension method for readability):
public static int Total(this IEnumerable<Item> items)
{
int confirmedTotal = 0;
int unconfirmedTotal = 0;
int unconfirmedCount = 0;
foreach (var item in items)
{
if (item.IsConfirmed)
{
confirmedTotal += item.Qty;
}
else
{
unconfirmedCount++;
unconfirmedTotal += item.Qty;
}
}
if (unconfirmedCount == 0)
return confirmedTotal;
// NOTE: Will not throw if there is no unconfirmed items
return confirmedTotal + unconfirmedTotal / unconfirmedCount;
}
Usage is simple:
items.Total();
BTW Second solution from accepted answer is not correct. It's just a coincidence that it returns correct value, because you have all unconfirmed items with equal Qty. This solution calculates sum instead of average. Solution with grouping will look like:
var total =
items.GroupBy(i => i.IsConfirmed)
.Select(g => g.Key ? g.Sum(i => i.Qty) : (int)g.Average(i => i.Qty))
.Sum();
Here you have grouping items into two groups - confirmed and unconfirmed. Then you calculate either sum or average based on group key, and summary of two group values. This also neither readable nor efficient solution, but it's correct.

Select All distinct values in a column using LINQ

I created a Web Api in VS 2012.
I am trying to get all the value from one column "Category", that is all the unique value, I don't want the list to be returned with duplicates.
I used this code to get products in a particular category. How do I get a full list of categories (All the unique values in the Category Column)?
public IEnumerable<Product> GetProductsByCategory(string category)
{
return repository.GetAllProducts().Where(
p => string.Equals(p.Category, category, StringComparison.OrdinalIgnoreCase));
}

To have unique Categories:
var uniqueCategories = repository.GetAllProducts()
.Select(p => p.Category)
.Distinct();

var uniq = allvalues.GroupBy(x => x.Id).Select(y=>y.First()).Distinct();
Easy and simple

I have to find distinct rows with the following details
class : Scountry
columns: countryID, countryName,isactive
There is no primary key in this. I have succeeded with the followin queries
public DbSet<SCountry> country { get; set; }
public List<SCountry> DoDistinct()
{
var query = (from m in country group m by new { m.CountryID, m.CountryName, m.isactive } into mygroup select mygroup.FirstOrDefault()).Distinct();
var Countries = query.ToList().Select(m => new SCountry { CountryID = m.CountryID, CountryName = m.CountryName, isactive = m.isactive }).ToList();
return Countries;
}

Interestingly enough I tried both of these in LinqPad and the variant using group from Dmitry Gribkov by appears to be quicker. (also the final distinct is not required as the result is already distinct.
My (somewhat simple) code was:
public class Pair
{
public int id {get;set;}
public string Arb {get;set;}
}
void Main()
{
var theList = new List<Pair>();
var randomiser = new Random();
for (int count = 1; count < 10000; count++)
{
theList.Add(new Pair
{
id = randomiser.Next(1, 50),
Arb = "not used"
});
}
var timer = new Stopwatch();
timer.Start();
var distinct = theList.GroupBy(c => c.id).Select(p => p.First().id);
timer.Stop();
Debug.WriteLine(timer.Elapsed);
timer.Start();
var otherDistinct = theList.Select(p => p.id).Distinct();
timer.Stop();
Debug.WriteLine(timer.Elapsed);
}

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