Stacking in 3s

[takn25]

Hi, I want to know is there a simpler of achieving this. I have a table called part it has a row called HD.

The HD stores a number which is not unique. I will provide a visual example below to explain further.               

 

Table

  HD           

  42             

  42             

  42               

 

What I am after is a query something like Pile HD in stacks of 3. For example there are 3 HD with the number 42. That is 1 stack if there were 6 HD with the number 42 that would equal 2 stacks and so on. I can do some sort of maths to get the results but would like to know is there a query I can come up with to show how many stacks of 3 are there? 

 

[fugix]

you could probably make multiple queries using limits...but im not sure if that would be the most effective way..I'l try to come up with some more

[cssfreakie]

I just puzzled a bit and this is what i came up with. Not sure if it is the cleanest way, but it works. Love to hear a better way though

Note though this assumes you first fetch data, and let php do the puzzling

<?php
$myarray = array(
    42,42,42,60,60,60,60,60,60,60,50,50,50,40,40,50
);
sort($myarray); // added this to sort unsorted arrays
$i = 0;

foreach($myarray as $key => $value){
    if ($key !== 0){$num = $key - 1;}else{$num=0;} //mainly for the first array element
    if($i <= 2 &&  $myarray[$num] == $value){ // if previous value is the same as the current
        echo $value.'<br />';
        $i++;        
    }else{
        echo '<hr>'.$value.'<br />';
        $i = 1;
    }
}
?>

 

p.s. what wine and some cheese can come up with

 

edit: remove some redundant code

edit2: added a sorting thingy

[Pikachu2000]

SELECT ROUND((COUNT(HD) / 3), 2) AS n, HD FROM tbl_a GROUP BY HD ORDER BY HD DESC

[cssfreakie]

SELECT ROUND((COUNT(HD) / 3), 2) AS n, HD FROM tbl_a GROUP BY HD ORDER BY HD DESC

woO nice  cheers for sharing!