wpdb query not working

It’s probably because you must use % sign for “like” so it would be:

SELECT * FROM `wp_usermeta` 
WHERE meta_key= 'referrer' AND 
meta_value LIKE '%270%' AND 
meta_key= 'view_type' AND 
meta_value LIKE '%invoice%'

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)