通过索引提高数据库性能

The following code is exectued when i click on a button where the record in a database table(named order) is deleted and inserted into another database table(named complete) with same attributes!

<?php
     include("includes/db.php"); // contains database connection

    if( isset($_GET['del']) )
    {
        $id = $_GET['del'];

        $sql1="INSERT INTO complete
                   (`OrderNo.`,`NIC`,`DP`,`Address`,`DPTime`,`Telephone`,`Email`,
                    `Image1`,`ImageName1`,
                    `Image2`,`ImageName2`,
                    `Image3`,`ImageName3`) 

                  SELECT
                      `OrderNo.`,`NIC`,`DP`,`Address`,`DPTime`,`Telephone`,`Email`,
                      `Image1`,`ImageName1`,
                      `Image2`,`ImageName2`,
                      `Image3`,`ImageName3`
                    FROM `order`
                    WHERE `OrderNo.` = '$id'  ";
        $res1= mysqli_query($db,$sql1) or die("Failed".mysqli_error($db));

        $sql2= "DELETE FROM `order` WHERE `OrderNo.` = '$id' ";

        $res2= mysqli_query($db,$sql2) or die("Failed".mysqli_error($db));

        echo "<meta http-equiv='refresh' content='0;url=vieworders.php'>";

    }
?>

since the 'where' clause has 'Orderno.' attribute the efficiency of the database can be improved using an index for the orderNo. attribute! How can i achieve this? where do i need to put the query " CREATE INDEX orderindex on `order(OrderNo.) "?

You can just run an MySQL client (console mysql, phpMyAdmin, heidisql, workbanch) and execute it.