Consolidate many queries into one - mysql

Question

I'm looking to achieve my goals as described below using one single query, as opposed to multiple queries as I currently have to use.
The problem I am having is that data from the wp_usermeta table is stored as a meta_key/meta_value in 2x columns, as opposed to each type of data having it's own column. While the reasoning for this makes sense, it does mean I'm stumped at this point.
The database in question is for a WordPerss site, should anyone wish to replicate this.
My goals
For each user who has at least one image/video post I need to grab the following details -
+-----------------------+---------------+------------------------------------------------+
| Description | Table | Column |
+-----------------------+---------------+------------------------------------------------+
| User ID | `wp_users` | `ID` |
| Display Name | `wp_users` | `display_name` |
| First Name | `wp_usermeta` | `meta_value` (WHERE `meta_key` = 'first_name' |
| Description | `wp_usermeta` | `meta_value` (WHERE `meta_key` = 'description' |
| Facebook profile link | `wp_usermeta` | `meta_value` (WHERE `meta_key` = 'facebook' |
| Google+ profile link | `wp_usermeta` | `meta_value` (WHERE `meta_key` = 'google_plus' |
| Twitter profile link | `wp_usermeta` | `meta_value` (WHERE `meta_key` = 'twitter' |
+-----------------------+---------------+------------------------------------------------+
My current solution
First I select the ID and display name of all users who have at least 1 image/video post (this is one single query) -
SELECT DISTINCT `wp_users`.`ID`, `wp_users`.`display_name`
FROM `wp_posts`
INNER JOIN `wp_users`
WHERE `wp_posts`.`post_type` = "attachment"
AND `wp_posts`.`post_status` = "inherit"
AND `wp_posts`.`post_author` = `wp_users`.`ID`
AND (
`wp_posts`.`post_mime_type` LIKE "image%"
OR `wp_posts`.`post_mime_type` LIKE "video%"
)
Next, I have to loop through each result from the first query and select the first name, description and social media links for each (this is one example, for user_id = 2) -
SELECT `wp_usermeta`.`meta_key`, `wp_usermeta`.`meta_value`
FROM `wp_usermeta`
WHERE `wp_usermeta`.`user_id` = 2
AND (
`wp_usermeta`.`meta_key` = 'first_name'
OR `wp_usermeta`.`meta_key` = 'description'
OR `wp_usermeta`.`meta_key` = 'facebook'
OR `wp_usermeta`.`meta_key` = 'google_plus'
OR `wp_usermeta`.`meta_key` = 'twitter'
);
As part of the loop where the second query is run I also have to insert those results into the results from the first. All of this not only means extra code, but leads to a longer execution time.
My full code can be found here - http://pastebin.com/P2jv3WTt
Is this goal achievable with MySQL, or is it simply not something it is able to do? Thanks.
What I've tried
I have tried to join to the wp_usermeta table as follows, outputting the results as a named column, but there is an issue - the only results are for users who have an entry for every single meta_key in the wp_usermeta table, but some don't (no Twitter profile link, for example).
SELECT DISTINCT
u.`ID`,
u.`display_name`,
m1.`meta_value` AS first_name,
m2.`meta_value` AS description,
m3.`meta_value` AS facebook,
m4.`meta_value` AS google_plus,
m5.`meta_value` AS twitter
FROM `wp_users` u
JOIN `wp_posts` p
JOIN `wp_usermeta` m1 ON (m1.user_id = u.id AND m1.meta_key = 'first_name')
JOIN `wp_usermeta` m2 ON (m2.user_id = u.id AND m2.meta_key = 'description')
JOIN `wp_usermeta` m3 ON (m3.user_id = u.id AND m3.meta_key = 'facebook')
JOIN `wp_usermeta` m4 ON (m4.user_id = u.id AND m4.meta_key = 'google_plus')
JOIN `wp_usermeta` m5 ON (m5.user_id = u.id AND m5.meta_key = 'twitter')
WHERE p.`post_type` = "attachment"
AND p.`post_status` = "inherit"
AND p.`post_author` = u.`ID`
AND (
p.`post_mime_type` LIKE "image%"
OR p.`post_mime_type` LIKE "video%"
)
ORDER BY RAND()

Answer 1

Most straightforward solution would be like this. Simply do a join for each meta-value you need.
By using LEFT OUTER JOIN instead of INNER JOIN to join the meta-data, you will still keep users for which some of these meta-data don't exist.
SELECT DISTINCT u.ID, u.DisplayName,
fn.meta_value AS firstname, fb.meta_value AS facebook, (etc.)
FROM wp_Users u
INNER JOIN wp_posts p ON p.post_author = u.ID
LEFT OUTER JOIN wp_usermeta fn ON fn.UserId = u.ID AND fn.meta_key = 'first_name'
LEFT OUTER JOIN wp_usermeta fb ON fb.UserId = u.ID AND fb.meta_key = 'facebook'
--- (etc. for each meta column you need to join)
WHERE p.post_type = 'attachment'
AND p.post_status = 'inherit'
AND (p.post_mime_type LIKE 'image%'
OR p.post_mime_type LIKE 'video%')

Answer 2

I would go with something like this:
SELECT DISTINCT
`wp_users`.`ID`,
`wp_users`.`display_name`,
`wp_usermeta`.`meta_key`,
`wp_usermeta`.`meta_value`
FROM
`wp_posts`
INNER JOIN
`wp_users` ON (`wp_posts`.`post_author` = `wp_users`.`ID`)
LEFT JOIN
`wp_usermeta` ON (`wp_usermeta`.`user_id` = `wp_users`.`ID`)
WHERE
`wp_posts`.`post_type` = 'attachment'
AND `wp_posts`.`post_status` = 'inherit'
AND (`wp_posts`.`post_mime_type` LIKE 'image%'
OR `wp_posts`.`post_mime_type` LIKE 'video%')
AND `wp_usermeta`.`meta_key`
IN ('first_name', 'description', 'facebook', 'google_plus', 'twitter');
LEFT JOIN must return you posts and users even if there are no meta associated with users.

Answer 3

are you looking for something like this?
SELECT meta.user_id, meta.meta_key, meta.meta_value
FROM wp_usermeta meta JOIN wp_posts posts
ON posts.post_author = meta.user_id
WHERE posts.post_type = "attachment"
AND posts.post_status = "inherit"
AND posts.post_mime_type RLIKE "^(image|video)"
AND meta_key IN ('first_name', 'description','facebook','google_plus','twitter');
Keep in mind that wp_posts.post_author and wp_usermeta.user_id should be indexes, otherwise this query will be slow.
Better yet if you have a joined index on wp_usermeta: user_key (user_id, meta_key). You can add this with the following command:
ALTER TABLE wp_usermeta ADD KEY user_key(user_id, meta_key);
PS If you also need display_name from the wp_users table, then you have to join it too:
SELECT meta.user_id, users.display_name, meta.meta_key, meta.meta_value
FROM wp_usermeta meta JOIN wp_posts posts
ON posts.post_author = meta.user_id
JOIN wp_users users
ON users.id = meta.user_id
WHERE posts.post_type = "attachment"
AND posts.post_status = "inherit"
AND posts.post_mime_type RLIKE "^(image|video)"
AND meta_key IN ('first_name', 'description','facebook','google_plus','twitter');