Question

A bit on my layout (simplified):

users table
|userid|lastauth|

When a user logs in, lastauth is changed to the authid of the new login token.

auth table
|authid|token|

Given a token, I want to find out which userid it belongs to. I’m not sure if I’m using INNER JOINs right, but this SQL gives out an error:

SELECT users.userid 
FROM 'users' 
  INNER JOIN 'auth' on users.lastauth = auth.authid 
WHERE auth.token=1234567890abcdef

Answer 1

Don’t use single quotes for object names. They are only for character literals (where you didn’t use them):

SELECT users.userid 
FROM users 
  INNER JOIN auth on users.lastauth = auth.authid 
WHERE auth.token = '1234567890abcdef'

You probably mixing that up with those dreaded backticks in MySQL:

SELECT users.userid 
FROM `users`
  INNER JOIN `auth` on users.lastauth = auth.authid 
WHERE auth.token = '1234567890abcdef'

But as your table names are not reserved words, you don’t need any type of quotes around your object names.