Dynamic Columns in SQLNode

NODENAME_<COLUMN_NUM>

but where  is dynamic.

For example if 

testCounter=1

SQLQuery3040_1 works, but i want to make the _1 be dynamic, what would be the syntax? I've tried
SQLQuery3040_testCounter
SQLQuery3040_<.!testCounter>
'SQLQuery3040_'+testCounter 
and countless others

It sounds like you are trying to use a single variable as a reference, and loop through all SQL node output fields using that one reference?  Something like this:

ref_var = 1;
while (ref_var <= 20) {
   save_var = SQLNode100_ref_var;
   ...
   do stuff with savevar value
   ...
   ref_var++;
}

Unfortunately, I don't think you can reference the node output values using variables this way - as least I've never found a way to do it.  I'd love for someone to prove me wrong...

Do you have a huge number of fields being returned?  What exactly are you trying to do?  Maybe there is another way.

I could envision changing your SQL query to output a delimited file, and then use the DataIterator node to parse it for processing. 

You could also build a delimited file from your SQL using JavaScript, but you'd have to allow for the maximum number of fields that could be returned.  Then you could follow that with a data iterator.

if ((SQLNode1000_1 !== "undefined" && SQLNode1000_1.length > 0)) {
    csv_string = SQLNode1000_1;
    csv_string += ",";
}
if ((SQLNode1000_2 !== "undefined" && SQLNode1000_2.length > 0)) {
    csv_string = SQLNode1000_2;
    csv_string += ",";
}
...
etc.