Question

I have a question regarding performance when using OOP in PHP together with databases. I’ll ask my question by example, suppose a class foo represents a row from some table. Now suppose I need to use foo at 5 different pages on my web app.

The catch is that on each of the 5 pages I will use data from different columns. (i.e. the first page will use column1 and column2 while the second page uses column3 and column 4, etc..)

The OOP approach (as far as I can see) would suggest that when I initialize foo on some particular row I would connect and fetch all the columns of that row and build my object. I could then proceed with my logic and use whatever data that I might need.

The issue I have with this is that with the procedural approach (which I’m more used to when it comes to web) would not waste resources to download columns that I do not need since the query would be specifically tailored to the needs of the particular page.(i.e. If im on the first page I would only download column1 and column2 since that’s what I need.)

Am i going about the OOP approach wrong or is the extra overhead so insignificant that developers in general download data which they do not need?

Thanks and sorry if this has already been covered, I thought it would be an interesting topic! 🙂

Erik

further clarification:

The class is like:

class foo
{
  $column1;
  $column2;
  $column3;
  $column4;

  public function _construct($id)
  {
    //get column 1,2,3 and 4 from database where table_id = $id
  }
}

The issue is that if i only need column1 one one page i download column2,3 and 4 for nothing. In procedural approach you would not do that. Is my OOP model bad or is this ok?

Answer 1

You can still incorporate the selective query inside of an OOP class by using either an array of columns to grab upon construction, or by using a public class method to handle the query grabbing.

Example of constructor:

<?php

class Foo{
    public function __construct( $column ) {

        if(is_array($column)){
             if(count($column) > 1){
                 $result = mysql_query('SELECT `'.implode('`,`', $column).'` FROM `table`;');
             }else{
                 $result = mysql_query('SELECT `'.$column[0].'` FROM `table`;');
             }
        }else{
             $result = mysql_query('SELECT `'.$column.'` FROM `table`;');
        }

        $this->result = mysql_result($result, 0);
    }
}
?>

The public function method would be identical to that, except you could return the result instead of setting $this->result.