Question

My application requires to create a stock management table which has a lot of items categorised into subgroups. For and idea, the stock management table looks like:

                           Location1             Location2                Total
Desktops    // Main Category
Microsoft   //Sub-Category

Windows 7                    23000                 150000                173000
Office 2011                 203300                   3002                206302 
....

Apple       //Sub-Category
OS Snow Leopard              4000                    3000                  7003
OS Lion                     39494                   40034                 79528
...

Tablets    //Main Category
Lenovo     //Sub-Cateogry

LX-243                       3434                   4399                   7833
...

This is a visualisation of what the table should look like, now i have a huge mysql query which does that for me, it is scary. In a gist, what i am doing is the following:

1. Select 1st category and start a while loop
   // echo as the main category
2. Select sub-category corresponding to the main category and start a while loop again.
   // echo as the sub-category
3. select all items in the sub-category and start a while loop.
4. select 1st location.
5. select the current item from 3 and the current location from 4 and echo item.
   // echo item names and the quantity in the locations.

Now my question here is is there a better way to display this than using several while loops, i tried using functions but they are becoming a mess too. Also i couldn’t figure out where should i perform the calculations to get the total in the last column.

Database structure:

Category: CategoryID, Description
Sub-Cateogry: Sub-Category_ID, Category_ID, Description
Item: Item_ID, Sub-category_id, Description
Location: Location_ID, Description
Stock_Management: Item_ID, Location_ID, Quantity

Code as requested:

$sql = mysql_query("select Board_ID, Title from Board where Company_ID = '$company_id' order by Title");

while($row = mysql_fetch_array($sql)) {
        $curr_ID = $row[0];
        $curr_category = $row[1];
        echo "<tr class='sub-heading' style='background: rgba(76, 178, 255, 0.1)'><td colspan='".$count."'>".$curr_category."</td></tr>";
        $sql1 = mysql_query("select Sub_Category_ID, Title from Sub_Category where Category_ID = '$curr_ID' order by Title");
        while($row1 = mysql_fetch_array($sql1)) {
            $curr_sub_cat_id = $row1[0];
            $curr_sub_cate = $row1[1];
            echo "<tr style='background: rgba(149, 255, 145, 0.10'><td colspan='".$count."'><b>".$curr_sub_cate."</b></td></tr>";
            $sql2 = mysql_query("select Book_ID, title from Book where sub_category_id = '$curr_sub_cat_id' Order by title");
            while($row2 = mysql_fetch_array($sql2)) {
                $curr_book = $row2[0];
                echo "<tr><td>".$row2[1]."</td>";
                $sql4 = mysql_query("select OfficeID, OfficeTitle from Office where OfficeTitle IN ('$locations')");
                while($row3 = mysql_fetch_array($sql4)) {
                    $curr_location = $row3[0];
                    $sql3 = mysql_query("select Quantity from Stock_Management where Book_ID = '$curr_book' and Location_ID = '$curr_location'");
                    while($row3 = mysql_fetch_array($sql3)) {
                        echo "<td>".$row3[0]."</td>";
                    }   
                }
                echo "</tr>";
            } 
        }
    }

Answer 1

How about something like this –

<?php

$locations = array('Location 1', 'Location 2', 'Location 3');
$locationCols = array();
$locationList = array();

foreach ($locations as $location) {
    $locationColName = preg_replace('[^a-z0-9]', '_', strtolower($location));
    $location = mysql_real_escape_string($location);
    $locationCols[] = "SUM(IF(Office.OfficeTitle = '$location', Stock_Management.Quantity, 0)) AS `$locationColName`";
    $locationList[] = "'$location'";
}
$locationCols = implode(', ', $locationCols);
$locationList = implode(',', $locationList);

$sql = "SELECT Board.Title AS BoardTitle, Sub_Category.Title AS SubCatTitle, Book.title AS BookTitle, $locationCols, SUM(Stock_Management.Quantity) AS Total
        FROM Board
        INNER JOIN Sub_Category
            ON Board.Board_ID = Sub_Category.Category_ID
        INNER JOIN Book
            ON Sub_Category.Sub_Category_ID = Book.sub_category_id
        INNER JOIN Office
        LEFT JOIN Stock_Management
            ON Book.Book_ID = Stock_Management.Book_ID
            AND Office.OfficeID = Stock_Management.Location_ID
        WHERE Board.Company_ID = 2
        AND Office.OfficeTitle IN ($locationList)
        GROUP BY Board.Title, Sub_Category.Title, Book.title";

$result = mysql_query($sql);

$prevBoard = '';
$prevSubCat = '';

echo '<table>';

while ($row = mysql_fetch_object($result)) {

    // if new board print board
    if ($prevBoard != $row->BoardTitle) {
        echo '<tr class="sub-heading" style="background: rgba(76, 178, 255, 0.1)"><td colspan="">' . $row->BoardTitle . '</td></tr>';
    }
    $prevBoard = $row->BoardTitle;

    if ($prevSubCat != $row->SubCatTitle) {
        echo '<tr style="background: rgba(149, 255, 145, 0.10)"><td colspan=""><b>' . $row->SubCatTitle . '</b></td></tr>';
    }
    $prevSubCat = $row->SubCatTitle;

    // print product row
    echo '<tr>';
    echo "<td>{$row->BookTitle}</td>";

    foreach ($locations as $location) {
        $locationColName = preg_replace('[^a-z0-9]', '_', strtolower($location));
        echo "<td>{$row->$locationColName}</td>";
    }

    echo "<td>{$row->Total}</td>";
    echo '</tr>';
}

echo '<table>';