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Question

有没有办法运行一个 mysql查询并获取多维数组？

例如，假设您有一个特定用户，并且您想要获取该用户的数据以及该用户的最新事件/活动。

表结构类似于：

users表：

ID | username | emailaddress | firstname | lastname | dateofbirth

events表：

ID | user | event_label | timestamp

当然只能有一个唯一身份用户，但该用户可以有多个事件。因此，如果我在这两个表上执行LEFT JOIN，我将不得不使用while循环来获取所有事件行。但是在每次迭代中，我将再次从users表中获得相同的数据。

例如，查询的代码可能是这样的：

$mysqli = new mysqli(HOST, USER, PASSWORD, DATABASE);
$id = 123456;
$select = $mysqli->query("
  SELECT users.*, events.event_label, events.timestamp
  FROM users
    LEFT JOIN events ON users.id=events.user    
  WHERE users.id=$id
");
while ($row = $select->fetch_assoc()) {
    $result[] = $row;
}
echo "<pre>";
print_r($result);
exit("</pre>");

/*
Sample output:
    Array (
    [0] => Array
        (
            [id] => 1
            [username] => name
            [emailaddress] => joe@example.com
            [firstname] => Joe
            [lastname] => Test
            [dateofbirth] => 2015-07-10
            [event_label] => Subscribe
            [timestamp] => 2015-07-10 00:00:00
        )
    [1] => Array
        (
            [id] => 1
            [username] => name
            [emailaddress] => joe@example.com
            [firstname] => Joe
            [lastname] => Test
            [dateofbirth] => 2015-07-10
            [event_label] => Visit
            [timestamp] => 2015-07-10 01:00:00
        )
    [2] => Array
        (
            [id] => 1
            [username] => name
            [emailaddress] => joe@example.com
            [firstname] => Joe
            [lastname] => Test
            [dateofbirth] => 2015-07-10
            [event_label] => phonecall
            [timestamp] => 2015-07-10 03:00:00
        )
)
*/

期望的结果将如下所示。我知道我可以在PHP中重新排列数据，但我想知道是否可以用MySQL实现相同的目标。

/*
Desired output:
    Array (
    [0] => Array (
        [id] => 1
        [username] => name
        [emailaddress] => joe@example.com
        [firstname] => Joe
        [lastname] => Test
        [dateofbirth] => 2015-07-10
        [events] => Array (
                [0] => Array (
                     [event_label] => Subscribe
                     [timestamp] => 2015-07-10 00:00:00
                )
                [1] => Array (
                     [event_label] => Visit
                     [timestamp] => 2015-07-10 01:00:00
                )
                [2] => Array (
                     [event_label] => phonecall
                     [timestamp] => 2015-07-10 03:00:00
                )
        )
)
*/

Answer 1

您应该可以稍微更改Select声明，以便于处理：

$select = $mysqli->query("
  SELECT users.username,
  users.emailaddress,
  users.firstname,
  users.lastname,
  users.dateofbirth,
  events.event_label,
  events.timestamp
  FROM users
    LEFT JOIN events ON users.id=events.user    
  WHERE users.id=$id
");

然后修改你的while循环，这样你就可以在php中获取一个多维数组

while ($row = $select->fetch_assoc()) {
    $result[[$row['id']] = $row;
}