如何计算PHP / MySQL中多行上两列之间的时差

Question

I have this PHP Code:

    $sql="SELECT ticket_seq, SUM(TIMEDIFF(timeend, timestart)) as total FROM ticket_updates GROUP BY ticket_seq";
$rs=mysql_query($sql,$conn) or die(mysql_error());
if(mysql_num_rows($rs) > 0)
{
    while($result=mysql_fetch_array($rs))
    {
        $sql2="SELECT * from tickets where ticketnumber = '".$result["ticket_seq"]."' ";
        $rs2=mysql_query($sql2,$conn) or die(mysql_error());
        $result2=mysql_fetch_array($rs2);

        $sql3="SELECT * from customer where sequence = '".$result2["company"]."' ";
        $rs3=mysql_query($sql3,$conn) or die(mysql_error());
        $result3=mysql_fetch_array($rs3);

        if($result["total"] > $result3["support_hours"])
        {
            echo $result3["company"].' - '.$result["total"].'<br>';
        }
    }
}

but then when i echo $result["total"] i just get random numbers.

I am trying to select the time difference between timestart and timeend for multiple rows and add it together.

Answer 1

I think something like this will solve your issue

SELECT SUM(
   (SELECT TIMEDIFF(timeend, timestart) FROM ticket_updates GROUP BY ticket_seq)
)