Might want to use a left join to ensure you get user info returned even if there is no timesheet info for the user.
<?php
$sqlquery =
'Select
users.*,
timesheet.*
From users
Left Join timesheet ON users.username = timesheet.username
Where users.username = ' . $_SESSION['username']
?>
<?php
$sqlquery =
'Select
users.*,
timesheet.*
From users
Left Join timesheet ON users.username = timesheet.username
Where users.username = ' . $_SESSION['username']
?>