Mysql 非常pid，计算t1q、t2q、t3q，其中t1q是表1时记录数量的总和。to_id=10，t2q是表1_2时记录数量的总和。from_id=10，t3q是表3时记录数量的总和。某些_id=10。我们如何才能做到这一点？如果这是不可能的，我是否应该使用cr

---

非常pid，计算t1q、t2q、t3q，其中t1q是表1时记录数量的总和。to_id=10，t2q是表1_2时记录数量的总和。from_id=10，t3q是表3时记录数量的总和。某些_id=10。我们如何才能做到这一点？如果这是不可能的，我是否应该使用cron来准备中间表，其中包含使用forloops计算的数据。对不起，我没用。根据这个例子，是否有一种使用“case”的方法？似乎另一个答案是有效的。无论如何，谢谢你的帮助。也许你的答案是对的，但对我来说，产品id重复了很多次。哦，那么你说我的解决方案在没有实际尝试的情况下“不起作用”？那很酷。。。case-when的另一个解决方案也可以，但执行速度较慢，而且比我的解决方案复杂得多。但不管怎样。使用SQL解决问题总是有多种方法。我相信我的解决方案对你的问题来说是最优雅的。我在你回答后立即尝试了。当我尝试时，我得到了相同的pid重复多次。无论如何，我会再试一次。再给你一个。谢谢。对不起，我没有工作。根据这个例子，是否有一种使用“case”的方法？似乎另一个答案是有效的。无论如何，谢谢你的帮助。也许你的答案是对的，但对我来说，产品id重复了很多次。哦，那么你说我的解决方案在没有实际尝试的情况下“不起作用”？那很酷。。。case-when的另一个解决方案也可以，但执行速度较慢，而且比我的解决方案复杂得多。但不管怎样。使用SQL解决问题总是有多种方法。我相信我的解决方案对你的问题来说是最优雅的。我在你回答后立即尝试了。当我尝试时，我得到了相同的pid重复多次。无论如何，我会再试一次。再给你一个。谢谢。你的第二个答案很有效，谢谢。但当t1q、t2q或t3q中的最后一个为0时，它将忽略pids。我们能在1、0、0或5、0、2或0、5、1等情况下获得输出吗？您的第二个答案有效，谢谢。但当t1q、t2q或t3q中的最后一个为0时，它将忽略pids。我们能在像1，0，0或5，0，2或0，5，1这样的情况下得到输出吗？

select 
    sum(table1.quantity) as t1q, 
    sum(table1_2.quantity) as t2q, 
    sum(table3.quantity) as t3q, 
    table1.pid as pid
from table1 
    inner join table3 on table1.pid=table3.pid
    inner join table1 table1_2 on table1.pid=table1_2.pid 
where 
    table1.to_id=10 and 
    table3.some_id=10 and 
    table1_2.from_id=10 
group by pid;

Table1:
quantity, to_id, from_id, pid

6, 10, 999999, 345
4, 888999, 10, 345
3, 888999, 10, 345

Table1 (same table used twice as table1 and table1_2)
Table3

SELECT a.pid,
       b.t1q,
       c.t2q,
       d.t3q
 FROM (SELECT DISTINCT(pid) FROM table1 AS pid) a
 JOIN (SELECT pid, SUM(quantity) AS t1q FROM table1 WHERE to_id = 10 GROUP BY pid) b ON a.pid = b.pid
 JOIN (SELECT pid, SUM(quantity) AS t2q FROM table1 WHERE from_id = 10 GROUP BY pid) c ON a.pid = b.pid
 JOIN (SELECT pid, SUM(quantity) AS t3q FROM table3 WHERE some_id = 10 GROUP BY pid) d ON a.pid = d.pid

select 
    sum(table1.quantity) as t1q, 
    sum(table1_2.quantity) as t2q, 
    sum(table3.quantity) as t3q, 
    table1.pid as pid
from
    table1 
inner join
    table3
        on table1.pid=table3.pid
inner join
(
    SELECT
        pid,
        SUM(quantity) AS quantity
    FROM
        table1
    WHERE
        from_id = 10
    GROUP BY
        pid
) 
    table1_2
        on table1.pid=table1_2.pid 
where 
    table1.to_id=10 and
    table3.some_id=10
group by
    pid

select 
    table1.quantity    as t1q, 
    table1_2.quantity  as t2q, 
    table3.quantity    as t3q, 
    table1.pid         as pid
from
 (
    SELECT
        pid,
        SUM(quantity) AS quantity
    FROM
        table1
    WHERE
        to_id = 10
    GROUP BY
        pid
)
    table1
inner join
(
    SELECT
        pid,
        SUM(quantity) AS quantity
    FROM
        table3
    WHERE
        some_id = 10
    GROUP BY
        pid
)
    table3
        on table1.pid=table3.pid
inner join
(
    SELECT
        pid,
        SUM(quantity) AS quantity
    FROM
        table1
    WHERE
        from_id = 10
    GROUP BY
        pid
) 
    table1_2
        on table1.pid=table1_2.pid

SELECT
    COALESCE(table1.t1q, 0)           AS t1q,
    COALESCE(table1.t2q, 0)           AS t2q,
    COALESCE(table3.t3q, 0)           AS t3q,
    COALESCE(table1.pid, table3.pid)  AS pid
FROM
(
    SELECT
        pid,
        SUM(CASE WHEN   to_id = 10 THEN quantity ELSE 0 END) AS t1q,
        SUM(CASE WHEN from_id = 10 THEN quantity ELSE 0 END) AS t2q
    FROM
        table1
    WHERE
            to_id   = 10
        OR  from_id = 10
    GROUP BY
        pid
)
    table1
FULL OUTER JOIN
(
    SELECT
        pid,
        SUM(quantity) AS quantity
    FROM
        table3
    WHERE
        some_id = 10
    GROUP BY
        pid
)
    table3
        ON table1.pid = table3.pid

SELECT
    SUM(t1q)   AS t1q,
    SUM(t2q)   AS t2q,
    SUM(t3q)   AS t3q,
    pid
FROM
(
    SELECT pid, quantity AS t1q, 0 AS t2q, 0 AS t3q FROM table1 WHERE to_id = 10
    UNION ALL
    SELECT pid, 0              , quantity, 0        FROM table1 WHERE from_id = 10
    UNION ALL
    SELECT pid, 0              , 0       , quantity FROM table3 WHERE some_id = 10
)
    combined
GROUP BY
    pid