The * is supposed to be used whenever you choose to SELECT ALL data/fields that match your conditions, not when you specify whick field to choose data from.
A simple example:
$sql = "SELECT * FROM DataTable ORDER BY entryID DESC LIMIT 2, 6";
With a specified coloumn:
$sql = "SELECT passengerName FROM DataTable ORDER BY entryID DESC LIMIT 2, 6";
The last sql-statement specifies to choose data from the field "passengerName" in the table, therefor you can drop the * that will select/return data from all fields in the records that match your conditions.