Question

I have tables contracts and users and i need to show contracts sorted by concatecated fields from users table. (and need outer join here because there is not always user present for contract)

SELECT * 
FROM `contracts` 
LEFT OUTER JOIN `users` ON `users`.id = `contracts`.account_manager_id 
WHERE contracts.status != 'Archived'
ORDER BY CONCAT_WS(' ', IFNULL(`users.contact_first_name`, '')
   , IFNULL(`users.contact_last_name`, '')) 
LIMIT 0, 50

Problem: Unknown column users.contact_first_name

Answer 1

Remove the backticks here:

`users.contact_first_name`

Change to:

users.contact_first_name

Or if you really want to use backticks you can quote the table and column name separately:

`users`.`contact_first_name`