Question

Im building a simple album and track webapp but im getting into a pickle with retrieving the correct information and making it efficient. I’ve got two tables – album has about 500 items and track with about 5000.

So I start off with a the normal while loop:

$albumQuery = "SELECT * FROM `album` ORDER BY album ASC";
$albumDatabase = mysql_query($albumQuery, $admin) or die(mysql_error()); 

while($albumRow = mysql_fetch_array($albumDatabase)){
    $list = "";
    $list.="build some html for showing later";

this is where I get into an efficency problem:

    $trackQuery = "SELECT track, album FROM `track` WHERE album = '{$album}' ORDER BY filename ASC";
    $trackDatabase = mysql_query($trackQuery, $admin) or die(mysql_error());

    while($trackRow = mysql_fetch_array($trackDatabase)){
        $list.="track html info";
    }

    $listarray[] = $list;
}

natcasesort($listarray);

I then run a foreach later in the body

foreach ($listarray as $v){
    $first_letter = strtoupper(mb_substr($v,9,1));
    if($tmp!==$first_letter){
        $tmp = $first_letter;
        echo '<div class="alphaHolder">'.$tmp.'</div>';
    }
    echo $v;
}

This works perfectly, apart from probably being possibly massively inefficent.

I can get it to regurgitate all the info in the right way and order.

As an experiment I placed of the second while loop outside the parent loop and stuck this info into its own array. Then ran this:

foreach($trackArray as $k => $v){
    if(in_array($v['album'], $albumRow)){
        $list.="track html info";
    }
}

But then I realized that every time it runs through the parent loop its rerunning the foreach over the 5000 items then doing the in_array 500 times. This obviously takes ages and normally crashes the browser. Leading me to the original nested while loop being slightly more efficient and convoluted.

I have started thinking that array_intersect might be the solution but I don’t want to bark up the wrong tree.

There’s probably too many loops and what have you going on but I need the natural sort and the alpha/numerical heading regurgitation.

Screenie: http://ink361.com/#/photos/133115598501394804_9688917

Answer 1

You can first flip the array later check if the key exists. This will by much faster as its indexed searched unlike previous iterative search.

$flipped_$albumRow = array_flip($albumRow);
foreach($trackArray as $k => $v){
    if(isset($flipped_albumRow[$v['album']]))){ # <- line of interest.
        $list.="track html info";
    }
}