Hi Krishna,
This is very late to answer but thought it might be helpful if someone else is really thinking that multiple columns cannot be updated in a single update statement.
I could execute following update query for my project -
update performance.ziele set ziel = 'aaaa' , termin = 'hhdddd', fluss = 2222
where BANK = 'x' and ziele_user = 'y' and project = 'z'
The values I kept in single quotes since error was coming if table name or column names are written with double quotes.