mysql对另一个表上的所有行执行相同的计算

我已确定我的问题：

SELECT * 
FROM  `participation` 
LEFT JOIN parties ON parties.id = participation.party_id
WHERE  `riding_id` = 10001
AND  `election_id` = 41
ORDER BY num_votes DESC 
LIMIT 1

这准确地产生了我想要的结果

结果是该党的得票最多

---

现在我想对表的每一行执行相同的查询ridings 其中包含所有

骑行id

行。有点麻烦

我不想联接另一个表，但要遍历每一行，并在每一行上执行与上面相同的计算

比如：

SELECT * 
    FROM  `participation` 
    LEFT JOIN parties ON parties.id = participation.party_id
    WHERE  `riding_id` = "LOOP ALL riding_id IN ridings TABLE"
    AND  `election_id` = 41
    ORDER BY num_votes DESC 
    LIMIT 1

---

任何帮助都将不胜感激。

只需使用子查询即可：

SELECT * 
FROM  participation LEFT JOIN
      parties
      ON parties.id = participation.party_id
WHERE  riding_id IN (SELECT riding_id FROM ridings) AND
       election_id = 41
ORDER BY num_votes DESC 

但是，你不再是最能赢得选票的人。你得到了一切

下面是一种使用变量的方法，它可以为每个

骑行id

获得最高票：

SELECT *
FROM (SELECT *,
             (@rn := if(@r = riding_id, @rn + 1,
                        if(@rn := riding_id, 1, 1)
                       )
             ) as seqnum
      FROM  participation LEFT JOIN
            parties
            ON parties.id = participation.party_id CROSS JOIN
            (SELECT @rn := 0, @r := -1) params
      WHERE  riding_id IN (SELECT riding_id FROM ridings) AND
             election_id = 41
      ORDER BY riding_id, num_votes DESC 
     ) pp
WHERE seqnum = 1;

---

仅使用子查询很有诱惑力：

SELECT * 
FROM  participation LEFT JOIN
      parties
      ON parties.id = participation.party_id
WHERE  riding_id IN (SELECT riding_id FROM ridings) AND
       election_id = 41
ORDER BY num_votes DESC 

但是，你不再是最能赢得选票的人。你得到了一切

下面是一种使用变量的方法，它可以为每个

骑行id

获得最高票：

SELECT *
FROM (SELECT *,
             (@rn := if(@r = riding_id, @rn + 1,
                        if(@rn := riding_id, 1, 1)
                       )
             ) as seqnum
      FROM  participation LEFT JOIN
            parties
            ON parties.id = participation.party_id CROSS JOIN
            (SELECT @rn := 0, @r := -1) params
      WHERE  riding_id IN (SELECT riding_id FROM ridings) AND
             election_id = 41
      ORDER BY riding_id, num_votes DESC 
     ) pp
WHERE seqnum = 1;

---

谢谢Gordon-在第二个查询中-我得到错误“重复的列名'id'”，但我只看到一次对“id”的引用？@kreevp。这是因为

选择*

。实际上，你应该只列出你想要的列。谢谢戈登-在第二次查询中-我得到错误“重复的列名'id'”，但我只看到一次对“id”的引用？@kreevp。这是因为

选择*

。实际上，您应该只列出所需的列。