Mysql 从另一个select语句更新表

我试图通过从另一个表中选择数据来更新我的列。我提出了这个SQL，它将从两个表中选择数据并将其更新到我的主表中。如下所示

UPDATE activity a 
SET a.amount = v.amount, 
    a.count = v.count 
FROM ( SELECT id,
                Sum(actual) amount,
                Count(id)  count
         FROM   amount_first
         WHERE  status = 1
                AND updated >= 1538323200
                AND updated <= 1541001599
         GROUP  BY id
         UNION
         SELECT id,
                Sum(0) amount,
                0      count
         FROM   amount_second
         WHERE  type = 3
                AND created >= 1538323200
                AND created <= 1541001599
         GROUP  BY id ) v
WHERE v.id = a.playerid

然而，我得到了这个错误

错误代码：1064。您的SQL语法有错误；检查与您的MySQL服务器版本对应的手册，以了解第4行“从SELECT id、SUM实际金额、Countid count FROM i”附近使用的正确语法

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上面的语句哪里出错了？

MySQL不支持这种连接语法。您应该在活动表和子查询之间使用显式内部联接：

UPDATE activity a 
INNER JOIN
(
     SELECT id,
            Sum(actual) amount,
            Count(id)  count
     FROM   amount_first
     WHERE  status = 1
            AND updated >= 1538323200
            AND updated <= 1541001599
     GROUP  BY id
     UNION
     SELECT id,
            Sum(0) amount,
            0      count
     FROM   amount_second
     WHERE  type = 3
            AND created >= 1538323200
            AND created <= 1541001599
     GROUP  BY id
) v
    ON v.id = a.playerid
SET a.amount = v.amount, 
    a.count = v.count;