Php 如何更新SELECT语句的结果？

我有一张这样的桌子：

// notifications
+----+--------------+------+---------+------------+
| id |      event   | seen | id_user | time_stamp |
+----+--------------+------+---------+------------+
| 1  | vote         | 1    | 123     | 1464174617 |
| 2  | comment      | 1    | 456     | 1464174664 |
| 3  | vote         | 1    | 123     | 1464174725 |
| 4  | answer       | 1    | 123     | 1464174813 |
| 5  | comment      | NULL | 456     | 1464174928 |
| 6  | comment      | 1    | 123     | 1464175114 |
| 7  | vote         | NULL | 456     | 1464175317 |
| 8  | answer       | NULL | 123     | 1464175279 |
| 9  | vote         | NULL | 123     | 1464176618 |
+----+--------------+------+---------+------------+ 

我的问题是：

(SELECT id, event, seen, time_stamp 
 FROM notifications n
 WHERE id_user = :id AND seen IS NULL
)UNION
(SELECT id, event, seen, time_stamp
 FROM notification n
 WHERE id_user = :id AND seen IS NOT NULL
 LIMIT 2
)UNION 
(SELECT id, event, seen, time_stamp 
 FROM notifications n
 WHERE id_user = :id 
 ORDER BY (seen IS NULL) desc, time_stamp desc
 LIMIT 15
)
ORDER BY (seen IS NULL) desc, time_stamp desc;

---

现在，我正在尝试更新上面查询中匹配的行，并设置

seen=1

，如下所示：

UPDATE notifications SET seen = 1 WHERE /* the result of query above */

我该怎么做

---

注意：我还使用PHP和PDO来执行SELECT查询（如果知道这一点很重要的话）

---

我想你可以用where in子句。。但在这种情况下，你需要一个身份证

    UPDATE notifications SET seen = 1 WHERE id in (
    (SELECT id
     FROM notifications n
     WHERE id_user = :id AND seen IS NULL
    )UNION
    (SELECT id
     FROM notification n
     WHERE id_user = :id AND seen IS NOT NULL
     LIMIT 2
    )UNION 
    (SELECT id
     FROM notifications n
     WHERE id_user = :id 
     ORDER BY (seen IS NULL) desc, time_stamp desc
     LIMIT 15
    ))

---

我想你可以用where in子句。。但在这种情况下，你需要一个身份证

    UPDATE notifications SET seen = 1 WHERE id in (
    (SELECT id
     FROM notifications n
     WHERE id_user = :id AND seen IS NULL
    )UNION
    (SELECT id
     FROM notification n
     WHERE id_user = :id AND seen IS NOT NULL
     LIMIT 2
    )UNION 
    (SELECT id
     FROM notifications n
     WHERE id_user = :id 
     ORDER BY (seen IS NULL) desc, time_stamp desc
     LIMIT 15
    ))

---

您可以稍微修改查询以用作update语句的子查询：

UPDATE notifications SET seen = 1 WHERE id in (
    (SELECT id
     FROM notifications n
     WHERE id_user = :id AND seen IS NULL
    )UNION
    (SELECT id
     FROM notification n
     WHERE id_user = :id AND seen IS NOT NULL
     LIMIT 2
    )UNION 
    (SELECT id
     FROM notifications n
     WHERE id_user = :id 
     ORDER BY (seen IS NULL) desc, time_stamp desc
     LIMIT 15
    )
)

---

您可以稍微修改查询以用作update语句的子查询：

UPDATE notifications SET seen = 1 WHERE id in (
    (SELECT id
     FROM notifications n
     WHERE id_user = :id AND seen IS NULL
    )UNION
    (SELECT id
     FROM notification n
     WHERE id_user = :id AND seen IS NOT NULL
     LIMIT 2
    )UNION 
    (SELECT id
     FROM notifications n
     WHERE id_user = :id 
     ORDER BY (seen IS NULL) desc, time_stamp desc
     LIMIT 15
    )
)

---

我假设您已将所有适用的ID检索到应用程序中。你需要做的就是

UPDATE notifications
SET seen = 1
WHERE id IN (?,?,?)

---

其中，

？

被id值替换。

我假设您已将所有适用的id检索到应用程序中。你需要做的就是

UPDATE notifications
SET seen = 1
WHERE id IN (?,?,?)

---

其中，

？

被id值替换。

如果要在MySQL中执行此操作，请使用

JOIN

：

update notifications n join
       (select id
        from ((SELECT id, event, seen, time_stamp 
               FROM notifications n
               WHERE id_user = :id AND seen IS NULL
              ) UNION
              (SELECT id, event, seen, time_stamp
               FROM notification n
               WHERE id_user = :id AND seen IS NOT NULL
               LIMIT 2
              ) UNION 
              (SELECT id, event, seen, time_stamp 
               FROM notifications n
               WHERE id_user = :id 
               ORDER BY (seen IS NULL) desc, time_stamp desc
               LIMIT 15
              )) n
       ) nids
       on n.id = nids.id
    set seen = 1;

---

如果要在MySQL中执行此操作，请使用

JOIN

：

update notifications n join
       (select id
        from ((SELECT id, event, seen, time_stamp 
               FROM notifications n
               WHERE id_user = :id AND seen IS NULL
              ) UNION
              (SELECT id, event, seen, time_stamp
               FROM notification n
               WHERE id_user = :id AND seen IS NOT NULL
               LIMIT 2
              ) UNION 
              (SELECT id, event, seen, time_stamp 
               FROM notifications n
               WHERE id_user = :id 
               ORDER BY (seen IS NULL) desc, time_stamp desc
               LIMIT 15
              )) n
       ) nids
       on n.id = nids.id
    set seen = 1;

---

seen

只能是

1

或

null

。在这种情况下，您从UNION查询中获得的大部分信息都是无关的。在我看来，您尝试进行的更新的最终结果将是：

UPDATE notifications SET seen = 1 WHERE id_user = :id AND seen IS NULL

---

其他任何操作都将把已经

1

的内容更新为

1

可见的
只能是
1
或
空
。在这种情况下，您从UNION查询中获得的大部分信息都是无关的。在我看来，您尝试进行的更新的最终结果将是：

UPDATE notifications SET seen = 1 WHERE id_user = :id AND seen IS NULL

其他任何东西都会将已经
1
的东西更新为
1
老实说，我知道这一点。但我认为有一个更简单的解决办法。tnx无论如何，我的意思是我可以将ID的数量存储到一个PHP变量中，并在
update
语句中使用它吗？像这样的
更新。WHERE id IN（“.$ids.”）
是的，您可以在注释中使用格式化字符串，但也可以使用IN子句的数组。。。有一些关于stackoverflowWell的建议，老实说，我知道。但我认为有一个更简单的解决办法。tnx无论如何，我的意思是我可以将ID的数量存储到一个PHP变量中，并在
update
语句中使用它吗？像这样的
更新。WHERE id IN（“.$ids.”）
是的，您可以在注释中使用格式化字符串，但也可以使用IN子句的数组。。。有一些关于StackOverflow的建议是正确的，请告诉我如何从
$result=$stm->fetchAll（）提取所有ID
并将其用于
UPDATE
语句？没错，请您告诉我如何从
$result=$stm->fetchAll（）提取所有ID
并将其用于
UPDATE
语句？seen
可以使用哪些其他值？
seen
只接受两个值，
NULL
（未读消息），
1
（读取消息）seen

可以使用哪些其他值？

seen

只接受两个值，

NULL

（未读邮件），

1

（阅读邮件）