使用一个查询从两个 SQL 表分页。最快的方式

Question

我有一个简单的数据库：

Table 1: Object                    Table 2: Data
id | type | added                  object_id | key     | value
------------------------           -----------------------------
1  | app  | 2017                   1         | name     | ...
2  | app  | 2017                   2         | name     | ...
3  | win  | 2017                   2         | version  | ...
                                   2         | dev_name | ...
                                   2         | lang     | ...

我创建了一个简单的分页，仅显示类型应用程序中的 5 个对象及其数据表中的信息：

example code:
$sth = $dbh->prepare("SELECT * FROM object WHERE type = 'app' LIMIT 5");
$sth->execute;
$object = $sth->fetchAll(PDO::FETCH_ASSOC);

foreach($object as $rows) {
    $sth = $dbh->prepare("SELECT * FROM data WHERE id = $rows['id']");
    $sth->execute;
    $data = $sth->fetchAll(PDO::FETCH_ASSOC);

    echo $data['name'];
    echo $data['version'];
    echo $object['added'];
    ...

有没有更好的方法？因为这是一个非常糟糕的解决方案，所以我只想查询一次获得这样的 fetch 数组：

array(
       // app with id = 1 in object table
       [1] => array(
                     // data from the app with id = 1 in data table
                     [name] => ...
                     [version] => ...
                     [dev_name] => ...
                     [lang] => ...
       // app with id = 2 in object table
       [2] => array(
                     // data from the app with id = 2 in data table
                     [name] => ...
                     [version] => ...
                     [dev_name] => ...
                     [lang] => ...
...

Answer 1

一个查询：

SELECT * FROM object inner join data on data.id_object=object.id WHERE object.type = 'app' LIMIT 5

此查询从两个表中返回信息以及关联数据。 我想这就是你想要的

如果你想按第一个表的 id 分组，你也可以执行这个查询

SELECT * FROM object inner join data on data.id_object=object.id WHERE object.type = 'app' group by object.id LIMIT 5

或

SELECT Distinct(object.id), object.type, .... FROM object inner join data on data.id_object=object.id WHERE object.type = 'app'  LIMIT 5

考虑字符串比较使用 LIKE 而不是 =