join query not working properly - php

Question

I want to select two table values so I am using join query see below, from this code I stored one session variable like $_SESSION['emp_id'], I want select query like who are in te.emp_id='".$_SESSION['emp_id']."', From this code $count will return 0 but in my database I have one row.
$q = mysql_query("SELECT *
FROM task_employee te
JOIN task t
ON te.emp_id = t.t_assign_to
WHERE t.t_status = '0'
AND t.t_delete_on != '1'
AND te.emp_id = '" . $_SESSION['emp_id'] . "'");
$data = array();
while($r = mysql_fetch_assoc($q))
{
$data[] = $r;
}
$count = sizeof($data);
if($count > 0)
{
$return = array('status'=>'success', 'count'=>sizeof($data), 'data'=>$data);
echo json_encode($return);
}
else
{
$return=array('status'=>'not-found', 'count'=>sizeof($data), 'data'=>$data);
echo json_encode($return);
}
I am writing like this means I can get but using join query that time I can't get values
<?php
$sql = mysql_query("SELECT *
FROM task
WHERE t_delete_on !='1'
AND t_assign_to = '$emp_id'");
for ($i = 1; $row = mysql_fetch_assoc($sql); $i++)
{
$assign_to = $row['t_assign_to'];
$mysql = mysql_query("SELECT *
FROM task_employee
WHERE emp_id = '$assign_to'");
while ($r = mysql_fetch_assoc($mysql))
{
$emp_name = $r['emp_firstname']; // here i got value
}
}
?>