Merging Many to Many Results - mysql

Question

I'm using the following SELECT statement:
SELECT *
FROM prefix_site_tmplvars
LEFT JOIN prefix_site_tmplvar_contentvalues
ON prefix_site_tmplvar_contentvalues.tmplvarid = prefix_site_tmplvars.id
LEFT JOIN prefix_site_content
ON prefix_site_tmplvar_contentvalues.contentid = prefix_site_content.id
WHERE prefix_site_tmplvar_contentvalues.value = "chocolate"
This is what I get back:
[id] => 2
[name] => flavor
[value] => chocolate
[id] => 2
[name] => type
[value] => cookie
This is the result I'd like to get:
[id] => 2
[flavor] => chocolate
[type] => cookie
Is there a way to combine my results so I don't have a bunch of rows referring to the same ID? If now, how should I handle this?
I'm using Modx and this is working with the Template Variable tables: http://wiki.modxcms.com/index.php/Template_Variable_Database_Tables

Answer 1

You can just use case statements:
SELECT
id,
MAX( CASE WHEN name = 'flavor' THEN value ELSE NULL END ) AS flavor,
MAX( CASE WHEN name = 'type' THEN value ELSE NULL END ) AS type
FROM prefix_site_tmplvars
LEFT JOIN prefix_site_tmplvar_contentvalues
ON prefix_site_tmplvar_contentvalues.tmplvarid = prefix_site_tmplvars.id
LEFT JOIN prefix_site_content
ON prefix_site_tmplvar_contentvalues.contentid = prefix_site_content.id
WHERE prefix_site_tmplvar_contentvalues.value = "chocolate"
GROUP BY id
Of course, this approach only works if you know ahead of time what keys you want to select; but it seems like in this case you do know (flavor + type).

Answer 2

Problem is, you might have
{ "id": 2, "flavor": "chocolate", "type": "cookie" }
and another row with
{ "id": 3, "flavor": "vanilla", "calories": "375" }
...I don't think there's an easy way to solve the problem in MySQL; you'd need to decide what keys to look for.
On the other hand you can collapse the rows in PHP:
while($tuple = ...fetch tuple from mysql cursor...)
{
list ($id, $name, $value) = $tuple;
if (!isset($objs[$id]))
{
// You might want to add also "'id' => $id" to the array definition
$objs[$id]= array ($name => $value);
}
else
{
$obj = $objs[$id];
$obj[$name] = $value;
$objs[$id] = $obj;
}
}
Now $objs contains the desired data; you still need to get it back into Modx, though.

Answer 3

You can do this with a group by:
SELECT id,
max(case when name = 'flavor' then value end) as flavor,
max(case when name = 'type' then value end) as type
FROM prefix_site_tmplvars LEFT JOIN
prefix_site_tmplvar_contentvalues
ON prefix_site_tmplvar_contentvalues.tmplvarid = prefix_site_tmplvars.id LEFT JOIN
prefix_site_content ON prefix_site_tmplvar_contentvalues.contentid = prefix_site_content.id
WHERE prefix_site_tmplvar_contentvalues.value = "chocolate"
group by id