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

I have another table called users , the only important column there is ID , which I want to compare to the user_meta table rows.

The users table looks like:

ID    |    email   | etc...
1     |    email@test.com  |
5     |    testa@a.com   |
6     |    ....   |
7     |    ....   |

So say I have a table (user_meta) that looks like:

ID   |   userID   |   meta_key  |   meta_value
2    |   1        |   companyID |   2
3    |   1        |   user_type |   staff
4    |   5        |   companyID |   2
5    |   5        |   user_type |   staff
6    |   6        |   companyID |   4
7    |   6        |   user_type |   customer

I want to retrieve a single row for each userID , but only if the company ID and user_type are correct.

I want to retrieve all users that have the same companyID that I would send in the query, so let's say $companyID=2, and then all users that have the user_type ='staff'.

So user_meta.userID must equal users.ID, and user_meta.companyID must equal 2, and user_meta.user_type must equal 'staff'.

I want a list of all users that match these criteria.

A result would be userID 1 & 5 are returned. They both have companyID = 2 , and both have user_type = staff

Answer 1

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 2

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

Answer 3

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')
);