ว่าด้วยเรื่อง strtotime ในรูปแบบการค้นหาวันที่หน่อยครับ

<?php 
$hostname_connection = "localhost"; 
$database_connection = "dbname"; 
$username_connection = "root"; 
$password_connection = "123456"; 
 
$connection = mysql_pconnect($hostname_connection, $username_connection, $password_connection) or trigger_error(mysql_error(),E_USER_ERROR); mysql_query("SET NAMES UTF8") ;
 
mysql_select_db($database_connection, $connection); 
 
$query_rs_report_order_detail = "SELECT record.*, register.Emp_Name, department.Dep_Name, leave_type.Leave_Name, SUM(Rec_Day), SUM(Rec_Hour) FROM record inner join register on record.Emp_ID=register.Emp_ID inner join department on register.Dep_ID=department.Dep_ID inner join leave_type on leave_type.Leave_ID=record.Rec_Type where (( Date_start between '".$_POST['search_start']."' and '".$_POST['search_end']."') and (Date_end between '".$_POST['search_start']."' and '".$_POST['search_end']."' )) GROUP BY emp_id, Rec_Type ORDER BY record.Emp_ID ASC";
$rs_report_order_detail = mysql_query($query_rs_report_order_detail, $connection) or die(mysql_error()); 
$row_rs_report_order_detail = mysql_fetch_assoc($rs_report_order_detail); 
$totalRows_rs_report_order_detail = mysql_num_rows($rs_report_order_detail);
?>

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<form name="form1" method="post" action="">
          <p>&nbsp;</p>
          <p><BR>
            <BR>
          </p>
          <h4><img src="image/report.jpg" width="45" height="35"> รายงานสรุปวันลาพนักงานระหว่างวันที่ <U>"<?PHP echo"<font color=\"blue\">$search_start</font>";?>"</U> ถึง <U>"<?PHP echo"<font color=\"blue\">$search_end</font>";?>"</U></h4>
          <form name="form1" method="post" action="">
            ระหว่างวันที่ 
            <input type="text" name="search_start" id="search_start">
          ถึง 
          <input type="text" name="search_end" id="search_end">
          <input type="submit" name="button" id="button" value="ตกลง">
          <br>
          <br>
          </form>