Question

我想显示数据库表中的6条记录。 2个表之间存在一对多关系。使用自定义映射器，我将这些记录映射如下。

$result  = [
   0=>[
        "name"=>"jithin",
        "phone"=>"907856",
        "messages"=>[
                      0=>[
                          "title"=>"text messgae"
                         ],
                      1=>[
                          "title"=>"Data messgae"
                         ]
                    ]
      ],
    1=>[
        "name"=>"Rijin",
        "phone"=>"90247856",
        "messages"=>[
                      0=>[
                          "title"=>"text messgae"
                         ],
                      1=>[
                          "title"=>"Data messgae"
                         ]
                    ]
      ]
]

查询

"SELECT u.* , m.* FROM user u INNER JOIN messages m ON m.userId = u.id
 WHERE m.date BETWEEN "12-12-2015" AND "12-12-2018" LIMIT 0, 6;

此查询将返回

之类的数据

userId | name | messages|
-------|------|---------|
1      |jithin| hai     |
1      |jithin| hello   |
1      |jithin| Why?    |
2      |Rijin | hai     |
2      |Rijin | Where   |
2      |Rijin | Why?    |
-------------------------

但是我需要另外4个人的另外4条记录。我正在使用php和mysql5.7。

Answer 1

如果我了解您的需求：

    SELECT u.id, u.userName , m.message
    FROM user u 
    INNER JOIN messages m ON m.userId = u.id
    INNER JOIN (SELECT u.id as user_id FROM user u LIMIT 0, 6) as users
        ON users.user_id = u.id
    WHERE m.date BETWEEN '12-12-2015' AND '12-12-2018';

Answer 2

最后，我找到了这个问题的答案。

"SELECT u.* , m.* FROM user u 
 INNER JOIN messages m ON m.userId = u.id
 INNER JOIN (SELECT DISTINCT u.id as user_id FROM user u 
             INNER JOIN messages m ON m.userId = u.id
             WHERE m.date BETWEEN "12-12-2015" 
             AND "12-12-2018" LIMIT 0, 6) 
 AS distinct_users ON distinct_users.user_id=u.id
 WHERE m.date BETWEEN "12-12-2015" AND "12-12-2018";

这将返回准确的6个人消息，我们可以轻松管理分页。如果您还有另一个简单的选择。请在这里发布。

与PHP和MySQL的分页关系

2 个答案: