sorting in table and drop down

Hi all

I have 2 scenarios which require sorting functionality:

1. I have a table and wanted to know if we can allow user to sort by all the column of the table rather than the first column alone for ex say col 1 col2 and col3 are there in a table then presently I am able to only sort by col 1 can this functionality be extended to allowing user to sort the data by whichever column he/she selects.

2. I am populating user id in a drop down from ume so can i have that data sorted in alphabetical order.

Kindly provide me some help on how I can go about.

Thank you

Regards,

Preet