How To Convert The DataTable Column type?

Question

I am trying to implement:

dtGroupedBy.Compute(\"sum(POWER)\",dvv.RowFilter); 

It results of an error:

Invalid usage

Answer 1

You can't use the Sum() aggregate function on a string field.

There are 2 things you can do

• Redefine your existing column item in your db (or schema) to be a numeric field.(recommended)
• do a System.Int32 conversion on the data you're passing to the aggregate function. so you could do the following

dtGroupedBy.Compute("sum(CONVERT(" + POWER + ",'System.Int32'))",dvv.RowFilter);