We Love InnerHTML! - PHP

This article will show you the fastest way to order your database results, via JavaScript (with some work in PHP). It adds some more work to your script, but once you see the results you won't use the approach of adding the ORDER By clause anymore.

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By: Alvaro Calleja

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December 06, 2004

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Right now we have a table with its rows numbered. Each row's number is the ID of the product it contains. The idea of the fast sort is simple: to sort the table by, let's say, product's price we just need to know the order of the IDs when the products list is ordered by price. So we'll sort the products list by price with PHP's array functions, and pass the IDs to a JavaScript array, which will be used to reorder the rows of the table.

Hmm... I think it'll be easier with an example:

<?
//Connect to the database
$conn=mysql_connect('localhost','root','') or die ('Sorry, no connection to database available :-(');
//Perform our query
$query='SELECT * FROM test.products';
if (!$res=mysql_query($query, $conn))
{
die ('Sorry, query error');
}
//We populate the $output variable with the HTML code
to generate the results table
$output='<table><tr style="font-
weight:bold"><td>ID</td><td>NAME</td><td>PRICE</td><td>
CODE</td>
<td>WEIGHT</td></tr>';
//We keep the number of results of the query, they
will be used in JavaScript
$num_results=mysql_num_rows($res);
while ($a=mysql_fetch_row($res))
{
//Append the table row to our $output variable
$output.="<tr id='line$a[0]'><td>$a[0]</td><td>$a[1]
</td><td>$a[2]</td><td>$a[3]</td><td>$a[4]</td></tr>";

//Add this product to the prices array
$prices[$a[0]]=$a[2];
}
$output.='</table>';
//We now do the sorting of the prices array, and store
//it in a JS array
$jsOutput='var ordPrice=new Array(';
asort($prices, SORT_NUMERIC);
reset ($prices);
while (list ($key, $val) = each ($prices))
{
$jsOutput.= "$key,";
}
$jsOutput=substr($jsOutput,0,-1);
$jsOutput.=");\r\n";
//And we reverse the array to generate the inverse
//order JS array
$jsOutput.='var ordPriceInv=new Array(';
$prices=array_reverse($prices, TRUE);
reset ($prices);
while (list ($key, $val) = each ($prices))
{
$jsOutput.= "$key,";
}
$jsOutput=substr($jsOutput,0,-1);
$jsOutput.=");\r\n";
?>
<html>
<head>
<script language="JavaScript">
var num_results=<?=$num_results?>;
//We output the array definitions
<?=$jsOutput?>
//This is the function that performs the actual
//sorting
function order (field)
{
//This var will store the row number we are grabbing
// from the table
var row_number=0;

//We must generate again the table headers
var out='<table><tr style="font-
weight:bold"><td>ID</td><td>NAME</td><td>PRICE</td><td>
CODE</td><td>WEIGHT</td></tr>';
//The field variable is the name of the array we want
//to use to reorder our table
//We travel across it and grab the content of the row
//that has that ID, and append it to our out variable
for (x=0;x<num_results;x++)
{
eval ("row_number="+field+"["+x+"];");
eval ("out+=\"<tr id='line"+row_number+"'>\"+document.getElementById
('line"+row_number+"').innerHTML+'</tr>';");
}
out+='</table>';
//Finally, we set the innerHTML of the content div to
//our new table
document.getElementById('content').innerHTML=out;
}
</script>
</head>
<body>
<div id='content'>
<?=$output?>
</div>
<br><br> <input type="button" onClick="order
('ordPrice')" value="Order products by price">

<br><br> <input type="button" onClick="order
('ordPriceInv')" value="Order products by price
(inverse)">
</body>
</html>

Let's see what we've done. We have this PHP array $prices that holds the prices of the products, with its keys being the product's ID and its values the price of the product. We sort it numerically, and store its (now ordered by price) indexes in a JS array. If we reverse it, we can store its reverse ordered indexes in another JS array. This is what the JS arrays look like:

var ordPrice=new Array(10,1,9,2,5,4,6,3,7,8);
var ordPriceInv=new Array(8,7,3,6,4,5,2,9,1,10);

Then we have the JS order function, which accepts one parameter called field. This parameter is the name of the JS array we'll use to reorder the rows of our table. The function obtains the ID of the first product (following the new order), grabs the contents of its row and appends them to the output variable. Notice that since the innerHTML property stores only the contents of the TR tags, we must append manually the TR tags to the output variable, and that means setting the id too.

Once we have the HTML code of the new table, we just send it to the innerHTML property of the content object, which displays it immediately. Now, tell me, don't you love innerHTML? I personally think it's the best thing since sliced bread!

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