[英]Pagination from two SQL Tables with one query. Fastest Way
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,仅显示来自类型应用程序的 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'];
...
有没有更好的办法? 因为这是一个非常糟糕的解决方案,我只想查询一次我得到这样的获取数组:
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] => ...
...
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和关联数据。 我想这就是你想要的
如果要按第一个表的 id 分组,也可以执行此查询
SELECT * FROM object inner join data on data.id_object=object.id WHERE object.type = 'app' group by object.id LIMIT 5
或者
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 =
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