如何在 mysql 中使用 UNION 限制

Question

所以，我有这个问题。

我必须从内部联接中的不同表中获取多条记录并进入 UNION 或 UNION ALL 并使用限制进行一次分页，以下代码用于获取所有记录和计数。 这是我的克星：

(SELECT pp.id as id, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
        inner join users u ON pp.users_id $username
        inner join inn_oficial i ON i.photo_id = pp.property_id
        left join plans p ON pp.plans_id = p.id
        WHERE (pp.type = 1 or pp.type = 2) 
        $where ) 
       UNION 
        (SELECT pp.id as id, pp.*, i.model as name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
        inner join users u ON pp.users_id $username
        inner join rent_oficial i ON i.photo_id = pp.property_id
        left join plans p ON pp.plans_id = p.id
        WHERE pp.type = 3
        $where) 
       UNION 
        (SELECT pp.id as id, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
        inner join users u ON pp.users_id $username
        inner join fish_pay_oficial i ON i.photo_id = pp.property_id
        left join plans p ON pp.plans_id = p.id
        WHERE pp.type = 4
        $where ) 
       UNION 
        (SELECT pp.id as id, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
        inner join users u ON pp.users_id $username
        inner join stores_oficial i ON i.photo_id = pp.property_id
        left join plans p ON pp.plans_id = p.id
        WHERE pp.type = 5
        $where)
       UNION
        (SELECT pp.id as id, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
        inner join users u ON pp.users_id $username
        inner join transfer_oficial i ON i.photo_id = pp.property_id
        inner join plans p ON pp.plans_id = p.id
        WHERE pp.type = 6
        $where)
        GROUP BY pp.id
        ORDER BY pp.id

我从13.2.9.3 UNION Clause得到这个例子并尝试了脚本

当我尝试运行代码时出现错误

You have a syntax error in your SQL next to 'GROUP BY id ORDER BY id LIMIT 0.25' on line 1

对不起我糟糕的英语，这不是我的母语

Answer 1

我解决了 kskskskks，只需将 pp id 列添加为 id_p，然后按它排序

(SELECT pp.id as id_p, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
    inner join users u ON pp.users_id $username
    inner join inn_oficial i ON i.photo_id = pp.property_id
    left join plans p ON pp.plans_id = p.id
    WHERE (pp.type = 1 or pp.type = 2) 
    $where ) 
   UNION 
    (SELECT pp.id as id_p, pp.*, i.model as name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
    inner join users u ON pp.users_id $username
    inner join rent_oficial i ON i.photo_id = pp.property_id
    left join plans p ON pp.plans_id = p.id
    WHERE pp.type = 3
    $where) 
   UNION 
    (SELECT pp.id as id_p, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
    inner join users u ON pp.users_id $username
    inner join fish_pay_oficial i ON i.photo_id = pp.property_id
    left join plans p ON pp.plans_id = p.id
    WHERE pp.type = 4
    $where ) 
   UNION 
    (SELECT pp.id as id_p, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
    inner join users u ON pp.users_id $username
    inner join stores_oficial i ON i.photo_id = pp.property_id
    left join plans p ON pp.plans_id = p.id
    WHERE pp.type = 5
    $where)
   UNION
    (SELECT pp.id as id_p, pp.*, i.name, p.name as plans_name, u.username,u.email,u.phone, DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) as end_date FROM property_purchase pp
    inner join users u ON pp.users_id $username
    inner join transfer_oficial i ON i.photo_id = pp.property_id
    inner join plans p ON pp.plans_id = p.id
    WHERE pp.type = 6
    $where)
    ORDER BY id_p $pagination

Answer 2

LIMIT 0.25引起了我的怀疑，因为您提供的查询中没有表示此子句。

这并不重要，因为这看起来像一个XY 问题——我认为没有必要使用任何 UNION 子句或 GROUP BY。 您通过多次扫描整个表迫使您的服务器做太多工作，更不用说开发人员不得不阅读如此冗长和重复的查询的眼睛疲劳了。

我不知道$where里面有什么，但我的水晶球告诉我这不是安全的查询做法。 如果传入任何变量，我想使用准备好的语句。

如果您需要根据pp.type对列值进行个性化控制，那么您可以在 SELECT 中使用CASE表达式。

我认为您的查询可以归结为如下内容：

SELECT pp.*,
       i.name,
       p.name AS plans_name,
       u.username,
       u.email,
       u.phone,
       DATE_ADD(pp.init_date, INTERVAL pp.avaliable_days DAY) AS end_date
FROM property_purchase pp
JOIN users             u ON pp.users_id = u.id
JOIN inn_oficial       i ON pp.property_id = i.photo_id
LEFT JOIN plans        p ON pp.plans_id = p.id
WHERE pp.user_id = ?
    AND pp.type BETWEEN 1 AND 6
    $where
ORDER BY pp.id