Group Mysql Query With Nested Format - php

Question

I've searched through older threads but haven't yet found a solution for the following issue: is it possible to group and arrange mysql results without resorting to nested queries?
Please see the sample below.
I have:
Month Jan, Location USA, Program DDD
Month Jan, Location UK, Program EEE
Month Jan, Location USA, Program LLL
Month FEB, Location UAE, Program EEE
Month FEB, Location USA, Program DDD
Month FEB, Location UK, Program MMM
Month MAR, Location USA, Program FFF
Month MAR, Location UAE, Program FFF
Month MAR, Location UK, Program FFF
I want them to display like this:
+---------++---------++---------+
|Month Jan||Month Feb||Month Mar|
+---------------+---------++---------++---------+
|Location USA | || || |
+---------------+---------++---------++---------+
| |DDD ||DDD ||FFF |
+---------------+---------++---------++---------+
| |EEE || || |
+---------------+---------++---------++---------+
| |LLL || || |
+---------------+---------++---------++---------+
|Location UK | || || |
+---------------+---------++---------++---------+
| |EEE ||MMM ||FFF |
+---------------+---------++---------++---------+
|Location UAE | || || |
+---------------+---------++---------++---------+
| | ||EEE ||FFF |
+---------------+---------++---------++---------+
I have tried grouping the query but I'm unable to render it to the HTML table.
SELECT
event.`event_id`,
event.`event_program_id`,
event.`event_month`,
event.`event_location_id`,
location.`location_name`,
program.`program_name`,
program.`program_shortname`
FROM
`event`
LEFT JOIN
`location`
ON
event.`event_location_id` = location.`location_id`
LEFT JOIN
`program`
ON
event.`event_program_id` = program.`program_id`;
Right now its listing like this:
column1 column2 column3
line1 34
line2 34
line3 34
line5 34
Where I wanted like this:
column1 column2 column3
line1 34 34
34 34
34
line2 34
34 34 34
line3 34
line5 34

Answer 1

You can do some inner queries to achieve this for each column, if you have a predefined number of columns in the expected result, something like just the months of the year.
I had some experience with reports based on SQL that used subqueries like this, at the end of the day, this solution preved to be a pain to manage :) today I just read the data, store in a matrix in memory and at the end generate the result based on the matrix, much easier to change in the future.
cheers !
here is an example in PHP
<pre>
<?php
$columns = array();
$data = array();
// add the data from the database
$data["line1"]["column1"] += 34;
$data["line2"]["column1"] += 34;
$data["line3"]["column4"] += 34;
$data["line5"]["column2"] += 34;
$data["line1"]["column1"] += 34;
$data["line3"]["column4"] += 34;
// find the columns
foreach ($data as $line => $column) {
foreach ($column as $cname => $value) {
if( ! in_array($cname, $columns) ){
$columns[] = $cname;
}
}
}
sort($columns);
// display column names
echo " \t";
foreach ($columns as $index => $cname) {
echo $cname . "\t";
}
echo "\n";
// display the data
foreach ($data as $line => $column) {
echo $line . "\t";
foreach ($columns as $index => $cname) {
echo $column[$cname] . "\t";
}
echo "\n";
}
?>
</pre>
Here's another way to solve the problem
<pre>
<?php
$columns = array();
$data = array();
// add the data from the database
// sort the data in the SQL
$data[] = array("l" => "line1", "c"=> "column1", "v" => "AAA");
$data[] = array("l" => "line1", "c"=> "column1", "v" => "BBB");
$data[] = array("l" => "line1", "c"=> "column3", "v" => "CCC");
$data[] = array("l" => "line2", "c"=> "column2", "v" => "AAA");
$data[] = array("l" => "line3", "c"=> "column2", "v" => "AAA");
// find the columns
foreach ($data as $line => $column) {
if( ! in_array($column["c"], $columns) ){
$columns[] = $column["c"];
}
}
sort($columns);
// display column names
echo " \t";
foreach ($columns as $index => $cname) {
echo $cname . "\t";
}
echo "\n";
$name = '';
$count = 0;
// display the data
foreach ($data as $line => $column) {
if( $column['l'] == $name ){
$count ++;
} else {
$name = $column['l'];
$count = 0;
}
if( $count == 0 ){
echo $name . "\t";
} else {
echo " \t";
}
foreach ($columns as $index => $cname) {
if( $column['c'] == $cname ){
echo $column['v'] . "\t";
} else {
echo " \t";
}
}
echo "\n";
}
?>
</pre>
other reference using html as output
<table border="1">
<?php
$columns = array();
$data = array();
// add the data from the database
// sort the data in the SQL
$data[] = array("l" => "line1", "c"=> "column1", "v" => "AAA");
$data[] = array("l" => "line1", "c"=> "column1", "v" => "BBB");
$data[] = array("l" => "line1", "c"=> "column3", "v" => "CCC");
$data[] = array("l" => "line2", "c"=> "column2", "v" => "AAA");
$data[] = array("l" => "line3", "c"=> "column2", "v" => "AAA");
// find the columns
foreach ($data as $line => $column) {
if( ! in_array($column["c"], $columns) ){
$columns[] = $column["c"];
}
}
sort($columns);
// display column names
echo "<tr>";
echo "<td> </td>";
foreach ($columns as $index => $cname) {
echo "<td>".$cname."</td>";
}
echo "</tr>";
$name = '';
$count = 0;
// display the data
foreach ($data as $line => $column) {
echo "<tr>";
if( $column['l'] == $name ){
$count ++;
} else {
$name = $column['l'];
$count = 0;
}
if( $count == 0 ){
echo "<td>".$name."</td>";
} else {
echo "<td> </td>";
}
foreach ($columns as $index => $cname) {
if( $column['c'] == $cname ){
echo "<td>".$column['v']."</td>";
} else {
echo "<td> </td>";
}
}
echo "</tr>";
}
?>
</table>