Hi Ridhaa Hendricks,
if(isnull(AGENTNAME),'***NO angent***',AGENTNAME) as "oAGENTNAME";
it does not always work with isnull() i don't know why.
I use in these cases:
if(len(trim((AGENTNAME))=0, .. , ..)
the performance is not the best, but in works in all cases.
the trim removes Whitespaces in a string, so it would also test a ' ' as Null, but you can lease this out, obviously.