ทำ string ต่อเนื่อง ข้อมูลที่แสดงไม่ถูกต้องเกิดจากอะไรอ่ะครับ

<?php
$sql_lec = "SELECT * 
	FROM task_action AS a 
	INNER JOIN task_action_emp AS e ON a.task_ref=e.task_ref 
	INNER JOIN task_main AS m ON a.id=m.id 
	WHERE (e.task_confirm = 'Y') AND  (e.emp_status != '0') AND (a.task_flag is NULL) 
	AND (e.task_emp = '".$rec["task_emp"]."') 
	AND task_id = '0401' AND task_main = '41101' AND task_sub = '01' 
	AND ((a.datetime_start <= '$date_end_db 23:59')   AND  (a.datetime_end >='$date_start_db 00:00' )) 
";
$arr_lec = $objdb->getArray($sql_lec);
if (count($arr_lec) > 0)
{
	$i = 0;
	foreach ($arr_lec AS $lec)
	{
		$dv .= $i;
		echo $i;
		$i++;
	}
}
echo "<br>";
echo $dv;
?>