Update multiple rows using for loop and array php

You can execute one query only by using this :

$sql = "update live_tracking set swim_rank = '".$rank1[$i]."' WHERE id IN (";
for($i=0;$i<7;$i++){    
   $sql .= $id1[$i].",";
}

$sql .= ")";

$query = mysql_query($sql) or die("error : ".mysql_error());

if($query){
   echo "success";
} 

Execute the query within the loop itself.

    for($i=0;$i<7;$i++)
    {    
    mysql_query("update live_tracking set swim_rank = '".$rank1[$i]."' where id = '".$id1[$i]."'");
    }

I can see an error in the sql

$sql = "update live_tracking set swim_rank = '"$rank1[$i]."' where id = '".$id1[$i]."'";

The above should be

$sql = "update live_tracking set swim_rank = '".$rank1[$i]."' where id = '".$id1[$i]."'";

You were missing . in '".$rank1[$i]."'

It seems that you are on right track. but you need to execute query in the loop. like this:

$id1=array($aa1,$aa2,$aa3,$aa4,$aa5,$aa6,$aa7);
$rank1=array($a1,$a4,$a7,$a10,$a13,$a16,$a19);
require_once("connection.php");
for($i=0;$i<7;$i++){    
   $sql = "update live_tracking set swim_rank = '".$rank1[$i]."' where id = '".$id1[$i]."'";
   if(!mysql_query($sql)){
      echo "not updated".$id1[$i]; exit();  
   }


}