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Is Unpivot (Not Pivot) functionality available in Linq to SQL? How?


I have seen posts which would fetch you pivot results but not unpivot, Need to know if there is any clean way to achieve ? If not the any workaround would do as well ?

Execute this to see unpivot results in Management Studio

CREATE TABLE [dbo].[Payment](
    [PaymentId] [int] NOT NULL,
    [EmployeeId] [int] NOT NULL,
    [RegularHours] [decimal](18, 0) NULL,
    [OvertimeHOurs] [decimal](18, 0) NULL
) ON [PRIMARY]

go

insert into payment values (1, 1, 40,  10)
insert into payment values (1, 2, 20,  0)

go

select * from payment 

select * from payment unpivot ([hours] for [paytype] in ([RegularHours], [OvertimeHOurs]))a

The output for first Select statement

PaymentId   EmployeeId  RegularHours                            OvertimeHOurs
----------- ----------- --------------------------------------- 
1           1           40                                      10
1           2           20                                      0

(2 row(s) affected)

The output for second Select statement & this is what i am looking for

PaymentId   EmployeeId  hours                                   paytype
----------- ----------- ----------------------------------------------------- 
1           1           40                                      RegularHours
1           1           10                                      OvertimeHOurs
1           2           20                                      RegularHours
1           2           0                                       OvertimeHOurs

(4 row(s) affected)

Solution

  • Ok, I cant see a way you can do it where it is translated into SQL, below is what I have come up with but this is all performed managed code.

    Or... you can simply create a view in SQL.

    var payments = Payments.Select (p => new {
                                OvertimeHOurs = new {
                                        p.PaymentId,
                                        p.EmployeeId,
                                        Hours = p.OvertimeHOurs,
                                        PayType = "OvertimeHOurs"
                                        },
                                RegularHours = new {
                                        p.PaymentId,
                                        p.EmployeeId,
                                        Hours = p.RegularHours,
                                        PayType = "RegularHours"
                                        }
                                }
                    );
    var result = payments.Select(a => a.OvertimeHOurs).Union(payments.Select (p => p.RegularHours));
    result.Dump(); // LINQPad Method
    

    SQL Generated is

    -- Region Parameters
    DECLARE @p0 NVarChar(1000) = 'OvertimeHOurs'
    DECLARE @p1 NVarChar(1000) = 'RegularHours'
    -- EndRegion
    SELECT [t4].[PaymentId], [t4].[EmployeeId], [t4].[OvertimeHOurs] AS [Hours], [t4].[value] AS [PayType]
    FROM (
        SELECT [t1].[PaymentId], [t1].[EmployeeId], [t1].[OvertimeHOurs], [t1].[value]
        FROM (
            SELECT [t0].[PaymentId], [t0].[EmployeeId], [t0].[OvertimeHOurs], @p0 AS [value]
            FROM [payment] AS [t0]
            ) AS [t1]
        UNION
        SELECT [t3].[PaymentId], [t3].[EmployeeId], [t3].[RegularHours], [t3].[value]
        FROM (
            SELECT [t2].[PaymentId], [t2].[EmployeeId], [t2].[RegularHours], @p1 AS [value]
            FROM [payment] AS [t2]
            ) AS [t3]
        ) AS [t4]