SQL - How to concatenate this table? - mysql

Question

By running this SELECT query:
SELECT wp_posts.ID, wp_postmeta.meta_key, wp_postmeta.meta_value
FROM wp_posts
INNER JOIN wp_postmeta
ON wp_posts.ID = wp_postmeta.post_id
WHERE wp_posts.post_status = 'publish'
AND wp_posts.post_type = 'my_post_type'
AND wp_posts.post_date < NOW()
AND wp_postmeta.meta_key = 'wpcf-lat'
OR wp_postmeta.meta_key = 'wpcf-long'
I get table like this:
id meta_key meta_value
------------------------------
1270 wpcf-lat 12.6589
1270 wpcf-long 78.7425
1658 wpcf-lat 22.3654
1658 wpcf-long 65.2985
But I need result table to be like this
id wpcf-lat wpcf-long
------------------------------
1270 12.6589 78.7425
1658 22.3654 65.2985
How can I accomplish that?

Answer 1

For a known set of meta_key you can use the following query
select
wp.ID,
max(
case when pm.meta_key = 'wpcf-lat' then pm.meta_value end
) as `meta_value`,
max(
case when pm.meta_key = 'wpcf-long' then pm.meta_value end
) as `wpcf-long`
from wp_posts wp
join wp_postmeta pm on pm.post_id = wp.ID
group by wp.ID ;

Answer 2

A simple while or foreach in your PHP code is the easiest way to put the data in the format you need:
$query = '...';
$resultset = $DB->query($query);
$list = array();
while ($row = $resultset->fetchArray()) {
// Check if the entry having this ID was created before
$id = $row['id'];
if (! isset($list[$id]) {
// Create a new entry
$list[$id] = array(
'id' => $id,
'wpcf-lat' => NULL,
'wpcf-long' => NULL,
);
}
// Update the corresponding property
$key = $row['meta_key'];
$list[$id][$key] = $row['meta_value'];
}

Answer 3

As koushik veldanda said, you can need to pivot the table.
Something like:
SELECT wp_posts.ID,
CASE WHEN wp_postmeta.meta_key = 'wpcf-lat' THEN wp_postmeta.meta_value END AS wpcf-lat,
CASE WHEN wp_postmeta.meta_key = 'wpcf-long' THEN wp_postmeta.meta_value END AS wpcf-long
FROM wp_posts
INNER JOIN wp_postmeta
ON wp_posts.ID = wp_postmeta.post_id
WHERE wp_posts.post_status = 'publish'
AND wp_posts.post_type = 'my_post_type'
AND wp_posts.post_date < NOW()
AND wp_postmeta.meta_key = 'wpcf-lat'
OR wp_postmeta.meta_key = 'wpcf-long'
GROUP BY wp_posts.ID
I haven't tested this but it should be quite close.