Arla

So, I return data from a database, and first off, from my "standard" programming background, I was bringing the data back in Arrays, it all worked okay, but arrays have a few issues for what I was trying to do, but then I found DataTables, question is..

How much data can you bring back from a database in a datatable? And how efficient/inefficient are they? Example, if I'm bringing back one row of data, but my class has the datatable defined, should I bring all the data back in the datatable? Or just bring it back in individual variables, and leave the datatables for the bigger stuff?

Thoughts?