Question

This is the expression I’m trying to evaluate:

Sum(IIF(QUALITY<=9.0,1.0,0.0))

The problem is that

string expr = "Sum(IIF(QUALITY<=9.0,1.0,0.0))";
dataTable.Compute(expr, "")

throws an error saying

Syntax error in aggregate argument: Expecting a single column argument with possible 'Child' qualifier.

The main challenge is that I can’t rewrite the expression by hand, since it’s coming to my program in a string from an RDL file, so it originally looks like

Sum(IIF(Fields!QUALITY.Value<=9.0,1.0,0.0))

and my program needs to automatically convert that into a string that will be a valid expression when passed to dataTable.Compute(). I determined from Microsoft’s documentation of the Compute method that C# doesn’t like the “Fields!” or “.Value” parts of the syntax, and by removing them I have simpler expressions working fine; for example, these statements both return the expected values:

dataTable.Compute("Sum(QUALITY)");
dataTable.Compute("Count(QUALITY)");

Is it possible to do what I’m trying to do? I feel like I should just need a slight change in syntax somewhere for it to work, but I haven’t been able to find an answer on the internet and it’s getting pretty frustrating.

Here are some of the things I’ve tried so far, to no avail:

Sum(IIF([QUALITY]<=9.0,1.0,0.0))
Sum(Convert(IIF(QUALITY<=9.0,1.0,0.0), 'System.Double'))
Sum(IIF(Convert(QUALITY, 'System.Double')<=9.0,1.0,0.0))    

Answer 1

One way to do this might be to add an aggregate column to the DataTable with the Expression set to IIF(QUALITY<=9.0,1.0,0.0).

dataTable.Columns.Add("AggregateColumn", typeof(double), "IIF(QUALITY<=9.0,1.0,0.0)");

then sum or count the aggregate column.