MYSQL Select from tables based on multiple rows

Question

I have a table called user_meta. In that table I have the following columns: ID, userID, meta_key, meta_value

Answer 1

Not very sure about your question. I'm assuming this is what you may want:

select * from Users where ID in (
select userID from user_meta where (meta_key = 'companyID' and meta_value = 2) or (meta_key = 'user_type' and meta_value = 'staff')
);

Answer 2

You need to join with user_meta once for each attribute you want to match.

SELECT u.*
FROM users AS u
JOIN user_meta AS m1 ON u.id = m1.userID
JOIN user_meta AS m2 ON u.id = m2.userID
WHERE m1.meta_key = 'companyID' AND m1.meta_value = :companyID
AND m2.meta_key = 'user_type' AND m2.meta_value = 'staff'

Answer 3

SELECT `users`.`id`, 
       `Company`.`meta_value`, 
       `UserType`.`meta_value` 
FROM   `users` 
       JOIN `user_meta` `Company` 
         ON `Company`.`userid` = `users`.`id` 
       JOIN `user_meta` `UserType` 
         ON `UserType`.`userid` = `users`.`id` 
WHERE  `UserType`.`meta_value` = 'staff' 
       AND `Company`.`meta_value` = 2 

https://gyazo.com/de8d9124418f65b993d708c80c309325