Question

I am attempting to translate a SQL CASE statement but am running into some problems and was hoping I could get a hand. Here is the statement:

,SUM(CASE WHEN [Gads].[GadsEventTypeCode] IN ('D1', 'D2', 'D3', 'DP', 'PD', 'DM', 'D4')
    THEN [Allocation].[AllocatedEnergyMwh] ELSE 0 END / 
    CAST([Unit].[NetDependableCapacity] AS FLOAT)) AS Hrs_Derate

This is what I come up with but get “lost in translation”:

If [Gads].[GadsEventTypeCode] equals 'D1', 'D2', 'D3', 'DP', 'PD', 'DM', 'D4'
then Hrs_Derate equals the sum of:
[Allocation].[AllocatedEnergyMwh] / [Unit].[NetDependableCapacity]
else Hrs_Derate equals zero.

Answer 1

You have three elements that you need to translate:

1. CASE statement – this can be handled with a ternary expression, e.g., (cond) ? trueval : falseval
2. IN clause – there is the LINQ .Contains operator which can check if an element is contained inside an array.
3. Casting – the cast operator I believe is handled via the same methods in System.Convert.

Armed with these three translation rules, you would need something like this (untested):

var types = new [] { "D1", "D2", "D3", "DP", "PD", "DM", "D4" };

Hrs_Derate =
    ((types.Contains(gads.GadsEventTypeCode) ? allocation.AllocatedEnergyMwh : 0)
    / (Convert.ToFloat(unit.NetDependableCapacity))).Sum()