SELECT s.name
     , ( SELECT o.name
         FROM Options AS o
           JOIN Assoc AS a
             ON a.assoc_id = o.ID
         WHERE a.site_id = s.id
           AND a.assoc_type='option'
         ORDER BY o.id
         LIMIT 1 OFFSET 0
       ) AS option1
     , ( SELECT o.name
         FROM Options AS o
           JOIN Assoc AS a
             ON a.assoc_id = o.ID
         WHERE a.site_id = s.id
           AND a.assoc_type='option'
         ORDER BY o.id
         LIMIT 1 OFFSET 1
       ) AS option2
     , ( SELECT o.name
         FROM Options AS o
           JOIN Assoc AS a
             ON a.assoc_id = o.ID
         WHERE a.site_id = s.id
           AND a.assoc_type='option'
         ORDER BY o.id
         LIMIT 1 OFFSET 2
       ) AS option3
FROM Sites AS s

如果要对3个表执行通常的联接，要查找所有站点和相关选项，可以使用:

If you want to perform a usual join of the 3 tables, to find all sites and related options, you can use:

SELECT s.name AS site
     , o.name AS option
FROM Sites AS s
    JOIN Assoc AS a
        ON a.site_id = s.id
    JOIN Options AS o
        ON o.ID = a.assoc_id
WHERE a.assoc_type = 'option'
ORDER BY s.name
       , o.name