對兩個表的復雜查詢

Question

我有兩個表：

table1:
id
--
1
2
3

table2: (left out primary index)
id2 | cond
----------
3   | 1
3   | 0
2   | 1
2   | 1
2   | 0

我需要構造一個隱式計算此中間表的查詢：

temp:
id | c1 | c2
------------
1  | 0  | 2
2  | 2  | 2
3  | 1  | 2

與c1 = countRows(id2 == id && cone == 1)和c2 == countRows(id2 = 2 && cond == 1) 。

然后SELECT id FROM temp ORDER BY ABS(c1 - c2)*RAND() 。

我目前的嘗試有點像：

SELECT id, COUNT(t1.id2) AS c1, COUNT(t2.id2) AS c2
FROM table1 LEFT JOIN (table2 AS t1) ON id=t1.id2 LEFT JOIN (table2 AS t2) ON t2.id2=2
WHERE t1.cond=1 AND t2.cond=1
GROUP BY t1.id2
ORDER BY ABS(c1 - c2)*RAND()
LIMIT 1

其中有多個問題：

1. 它不會選擇table2中沒有條目的行
2. 它沒有正確計數
3. ORDER BY第3部分中的組列（c1，c2）似乎存在問題。

幫助將不勝感激。

---

更新：

• table1代表玩家
• table2將進行回合，cond表示獲勝
• c1代表每個玩家贏得的回合
• c2代表參考玩家（本例中為玩家2）贏得的回合

Answer 1

SELECT t1.id, SUM(IFNULL(t2.cond, 0) = 1) AS c1, (SELECT SUM(cond = 1) FROM table2 WHERE id2 = 2) AS c2
FROM table1 t1
LEFT JOIN table2 t2 ON t1.id = t2.id2
GROUP BY t1.id
ORDER BY ABS(SUM(IFNULL(t2.cond, 0) = 1) - c2) * RAND();

Answer 2

讓我們看看查詢的第一部分是否返回有效結果。

SELECT
    t1.id AS id
    COUNT(t2.id2) AS c1
    COUNT(CASE WHEN t3.id2 = 2 THEN t3.id2 ELSE NULL END) as c2
FROM
    table1 AS t1
    LEFT JOIN table2 as t2
        ON t1.id = t2.id2 AND t2.cond = 1
    LEFT JOIN table2 as t3
        ON t3.id2 = 2 AND t3.cond = 1

GROUP BY
    t2.id2,
    t3.id2

您可以提供架構嗎？