Select the table with a column that contains 'user_id'

gistfile1.txt

SELECT DISTINCT
    class.relname 
FROM
    pg_attribute AS att 
    INNER JOIN pg_class AS class 
        ON class.oid = att.attrelid 
WHERE
    att.attnum > 0 
    AND att.attname = 'user_id' 
    AND class.relkind = 'r' 
    AND class.relname ! ~ * '.*ba?k.*' 
ORDER BY
    class.relname ASC;