Question

It take 40 seconds to display data on the browser, that is not unacceptable.

Code below, it display all the from category.takeawayID=xxxxx and loop in items and options tables.

categories table: over 15,000 rows total

items table: over 100,000 rows

item_options table: over 150,000 rows.

How to improve the performance?

 $qcat = mysql_query("select * from categories where takeawayID=55276");
 while($c_row = mysql_fetch_assoc($qcat)) 
 {
     echo "<h2>" . $c_row['name'] . "</h2>";
     echo "<div>" . $c_row['description'] . "</div><br /> <br />";

     $qitem = mysql_query("select * from items where category_id =". $c_row['id']);

      while($i_row = mysql_fetch_assoc($qitem)) {
           echo "<div style='backround-color:pink'>" . $i_row['name'] . "</div>";

           $qoption = mysql_query("select * from item_options where item_id =". $i_row['id']);

           while($o_row = mysql_fetch_assoc($qoption)) {
               echo " (" . $o_row['price'] . ") ";
           }
      }
 }

Maximum records show between 200 to 500 rows depending on the takeawayID ID

Answer 1

You can make an effort to create a single query using joins and also make sure you have created indexes on the columns.

select * from categories c 
left join items t
on c.id= t.category_id
left join item_options io 
on t.id=io.item_id
Where c.takeawayID=55276