Yeah, I think you are going about it correctly. Flow chart is probably better.
You condition will need to convert the value to a number (Double) or integer (Int32). If you type
Convert., you should get a list in a dropdown, then look for
ToInt32. It will end up looking like this:
Convert.ToDouble( row("columnname").ToString.Trim ) >= 0
One direction will be the True side and one will be the False side. If you want to reverse the directions, just reverse the condition to < 0. In the Properties pane of the Decision activity, you can rename the True and False to whatever you desire as a label for what it is doing.
EDIT: Sorry, I realize you want to check if the data table has content. Then, you can use this:
dt1 isNot Nothing AndAlso dt1.Rows.Count > 0
That condition will check if dt1 has a value, and if true then check if the number of rows is > 0. That’s usually the ideal method to check.
I hope this helps.