Examples:
$q->table('user');
$q->table('user','u');
$q->table('user')->table('salary')
$q->table(array('user','salary'));
$q->table(array('user','salary'),'user');
$q->table(array('u'=>'user','s'=>'salary'));
If you specify multiple tables, you still need to make sure to add
proper "where" conditions. All the above examples return $q (for chaining)
You can also call table without arguments, which will return current table:
echo $q->table();
If multiple tables are used, "false" is returned. Return is not quoted.
Please avoid using table() without arguments as more tables may be
dynamically added later.