What Is the Equivalent of "Case When Then" (T-Sql) with Entity Framework

What is the equivalent of CASE WHEN THEN (T-SQL) with Entity Framework?

In this case, I'd say the conditional operator (p ? x : y) is a good substitute.

// context.MyTable is an IQueryable<MyTable>
var query = from t in context.MyTable
            group t by t.Code into grp
            select
            new {
                Code = grp.Key,
                Jan = grp.Sum(x => x.Month == 1 ? x.Days : 0),
            };

Or combine a Where and a Sum:

                Jan = grp.Where(x => x.Month == 1).Sum(x => x.Days),

I'm not sure what SQL these translate to exactly, but they should both have the same result.

Alternative to parameter for case statement

So instead of using the case statement with the parameter, use it as your filter. So your view would be something like (best practice is to always include schema on your objects, I assumed dbo):

view

select warehouse
     , productStatusId
     , productId
from dbo.products p
left join dbo.productstatus s on p.availability = s.cd;

query to use view

select productId
 , productStatusId
from schema.viewname
where warehouse = @warehouse;

another way to get all warehouse statuses

select cast(case when warehouse = @warehouse then 1 else 0 end as bit) as AtThisWarehouse, 
productStatusId
from schema.viewname;

SQL to LINQ - Case Statement

Try using ternary operator for all cases in your ThenBy clause:

 .ThenBy(x => x.column3 == "X" 
      ? 1 
      : x.column3 == "Y" 
          ? 2 
          : x.column3 == "Z" 
                ? 3 
                : defaultOrder)

How can I achieve SQL CASE statement from LINQ

You can use this if it suits you.
I would just explain the LINQ query part.
You can use this with EF. I created dummy data for these.
For EF, use IQueryable instead.

// from a row in first table
// join a row in second table
// on a.Criteria equal to b.Criteria
// where additional conditions
// select the records into these two fields called All and Range
// Convert the result set to list.
var query = (from a in lstCalc
join b in lstSampleSet
on a.SampleSetID equals b.ID where b.SampleDrawn >= DateTime.Now.AddMonths(-8)
&& b.Department == "Location A"
select new { All = 0, Range = Utilities.RangeProvider(a.Value) }).ToList();

EDIT : LINQ Query for grouped result.. Make sure you are using IQueryable.

 var query = (from a in lstCalc
  join b in lstSampleSet
  on a.SampleSetID equals b.ID where b.SampleDrawn >= DateTime.Now.AddMonths(-8) 
   && b.Department == "Location A"
    group a by Utilities.RangeProvider(a.Value) into groupedData
     select new Result { All = groupedData.Sum(y => y.Value), Range = 
   groupedData.Key }).ToList();

Here is the code for the same.

 public class Program
    {
        public static void Main(string[] args) {
            List<Calculation> lstCalc = new List<Calculation>();
            lstCalc.Add(new Calculation() {SampleSetID=1, Value=10 });
            lstCalc.Add(new Calculation() { SampleSetID = 1, Value = 10 });
            lstCalc.Add(new Calculation() { SampleSetID = 2, Value = 20 });
            lstCalc.Add(new Calculation() { SampleSetID = 3, Value = 30 });
            lstCalc.Add(new Calculation() { SampleSetID = 4, Value = 40 });
            lstCalc.Add(new Calculation() { SampleSetID = 5, Value = 50 });
            lstCalc.Add(new Calculation() { SampleSetID = 6, Value = 60 });
            lstCalc.Add(new Calculation() { SampleSetID = 7, Value = 70 });
            lstCalc.Add(new Calculation() { SampleSetID = 8, Value = 80 });
            lstCalc.Add(new Calculation() { SampleSetID = 9, Value = 90 });

            List<SampleSet> lstSampleSet = new List<SampleSet>();
            lstSampleSet.Add(new SampleSet() {Department = "Location A", ID=1, SampleDrawn=DateTime.Now.AddMonths(-5)});
            lstSampleSet.Add(new SampleSet() { Department = "Location A", ID = 2, SampleDrawn = DateTime.Now.AddMonths(-4) });
            lstSampleSet.Add(new SampleSet() { Department = "Location A", ID = 3, SampleDrawn = DateTime.Now.AddMonths(-3) });
            lstSampleSet.Add(new SampleSet() { Department = "Location A", ID = 4, SampleDrawn = DateTime.Now.AddMonths(-2) });
            lstSampleSet.Add(new SampleSet() { Department = "Location A", ID = 5, SampleDrawn = DateTime.Now.AddMonths(-2) });
            lstSampleSet.Add(new SampleSet() { Department = "Location A", ID = 6, SampleDrawn = DateTime.Now.AddMonths(-2) });
            lstSampleSet.Add(new SampleSet() { Department = "Location A", ID = 7, SampleDrawn = DateTime.Now.AddMonths(-1) });

            var query = (from a in lstCalc
                        join b in lstSampleSet
                        on a.SampleSetID equals b.ID where b.SampleDrawn >= DateTime.Now.AddMonths(-8)
                         && b.Department == "Location A"
                        select new { All = 0, Range = Utilities.RangeProvider(a.Value) }).ToList();

            Console.WriteLine(query.Count);
            Console.ReadLine();

        }

    }

        public class Utilities
        {
            public static string RangeProvider(int value)
            {
                if (value > 0 && value <= 25)
                { return "Low"; }
                if (value > 25 && value <= 75)
                { return "Medium"; }
                if (value > 75 && value <= 90)
                { return "High"; }
                else
                { return "Very High"; }
            }

        }

    public class Result {
      public int All { get; set; }
      public string Range { get; set; }
   }

    public class Calculation
    {
        public int SampleSetID { get; set; }
        public int Value { get; set; }

    }

    public class SampleSet
    {
        public int ID { get; set; }
        public DateTime SampleDrawn { get; set; }

        public string Department { get; set; }

    }

Entity Framework core how to use Case When statement

You can do like this.

DateTime dt1 = DateTime.Now;
DateTime dt2 = DateTime.Now;
DateTime dt3 = DateTime.Now;
DateTime dt4 = DateTime.Now;
var query = _context.Leave_Tbl.Sum(p => EF.Functions.DateDiffDay(dt1 > dt2 ? dt3 : dt4, dt1 > dt2 ? dt3 : dt4));

I have just taken these dates for simplicity.

Can you use a CASE statement with OrderBy in an LINQ to Entities query?

var p = ctx.People.OrderBy(p => (p.IsQualityNetwork == 1 || p.IsEmployee == 1) ? 0 : 1)
                  .ThenBy(p => p.Name);

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