DataTable.Select - Convert field type

Thanks for the points and grade.  I'm not sure I really deserve them, as I only suggested what you were doing anyway.

But I've given a bit more thought to "Any idea why?"

I reckon the docs are misleading.  The Remarks on the DataTable.Select(String,String) page [NET 2.0] says

>>
To form the filterExpression argument, use the same rules for creating the DataColumn class's Expression property value. The Sort argument also uses the same rules for creating class's Expression strings.
<<

But your experience shows that's not strictly true and, thinking about it, I think I can see why.  In effect, what .Select is doing is broadly equivalent to creating a DataView.  Not exactly equivalent - because it is returning datarows rather than datarowviews - but I imagine that, in the background, the same techniques are being used.  And, if that is correct, the first argument in this overload of DataTable.Select is equivalent to DataView.RowFilter - which will take an "Expression" - but the second is equivalent to DataView.Sort - which _won't_ take an "Expression".  That is limited to column/s and ASC or DESC.  

At a more conceptual level, an "Expression" in a RowFilter is, in effect, a test that can be and is applied on a record by record basis: this record meets the test and is to be included, that one fails it and is to be exlcuded.  But a Sort appears to require a "collection" - that is, all the data in given column/s - to operate.  And ("Convert(fundID, 'System.Int32')" is not such a "collection".  So, when it looks for the "collection" it is expecting - a column (or columns) - in the Sort argument, it errors out with the message you reported.

That's an empirical analysis.  I've no inside knowledge about what happens behind the scenes.  But it does answer your question about (possible) ideas why.  And, if it is correct, I think the implication is that there is no other workaround.

Roger