Question

我想以某种方式在foreach循环中对项目进行分组，以便我可以有效地显示它们。例如，如果我有以下MySql表：

user_id username group_id
1       John     1
2       Mark     2
3       Steve    2

我希望group_id 2中的用户一起显示在<div class="group2">Username 1: Mark, Username 2: Steve</div>中，用户显示在group_id 1 <div class="group1">Username John</div>

中

我希望你能理解这个问题。

Answer 1

您可以通过group_id订购查询，然后跟踪其更改时间，相当轻松地完成此操作。像这样：

$query = "SELECT * FROM table ORDER BY group_id";
$results = $mysqli->query($query);
$lastGroup = 0;
while ( $row = $results->fetch_assoc() )
{
    if ( $row['group_id'] != $lastGroup )
    {
        // If there is already a div open we need to close it, so if 
        // last group > 0 then a div has been opened.
        echo ($lastGroup > 0 ? '</div>' : '') . '<div class="group' . $row['group_id'] . '">';
    }
    $lastGroup = $row['group_id'];
    echo $row['username'] . '<br>';
}
// close the last open div
echo '</div>';

或者，您可以使用MySQL GROUP_CONCAT函数来获取组中的所有用户名。使用此：

$query = "SELECT group_id,
GROUP_CONCAT(username) as users
FROM table
GROUP BY group_id";

$results = $mysqli->query($query);
while ( $row = $results->fetch_assoc() )
{
    echo '<div class="group' . $row['group_id'] . '">' . $row['users'] . '</div>';
}

Answer 2

创建2D数组：

$users;

Foreach结果行$ row：

$users[$row->group_id][$row->user_id] = $row->username;

然后：

foreach($users as $group_id -> $group_users) {
    echo '<div class="' . $group_id . '">';
    foreach($group_users as $user_id -> $username) {
        echo " Username: ";
        echo $user_id;
        echo " :";
        echo $username;
    }
    echo "</div>";
}

Answer 3

强烈建议您使用mysql GROUPing函数制作查询，这样您就不必机械地执行此操作。但是，如果出于任何原因，您的结果集看起来像您发布的数据，并且您希望循环然后按照您的描述显示记录;您可以遍历行的数组，将同一组中的所有用户捆绑到一个唯一的子数组中，然后为显示运行foreach循环。下面的代码演示了如何使用示例：

    <?php

        // SIMULATE AN TO REPRESENT THE RECORDS FROM THE DB TABLE...
        $array = array(
            array(
                "user_id"   => 1,
                "username"  => "John",
                "group_id"  => 1,
            ),
            array(
                "user_id"   => 2,
                "username"  => "Mark",
                "group_id"  => 2,
            ),
            array(
                "user_id"   => 2,
                "username"  => "Steve",
                "group_id"  => 2,
            ),
        );

        // CREATE AN ARRAY FOR USE IN GROUPING USERS WITH THE SAME group_id
        $groupArray = array();

        // WALK THE SIMULATED ARRAY (IN YOUR CASE YOUR ROWS)
        // AND BUILD UP THE $groupArray
        $result     = array_walk($array, function($data) use(&$groupArray) {
            if(!array_key_exists($data['group_id'], $groupArray)){
                $groupArray[$data['group_id']][]        = $data;
            }else{
                if(!in_array($data, $groupArray)){
                    $groupArray[$data['group_id']][]    = $data;
                }
            }
        });

        // CREATE AN OUTPUT TO HOLD THE HTML CONTENT FOR DISPLAY:
        $output     = "";

        // LOOP THROUGH THE $groups AND BUILD UP YOUR DATA...
        foreach ($groupArray as $groupID=>$groups){
            $output.= "<div class='group" . $groupID . "'>" . PHP_EOL;
            $output.= "<h3 class='group-users'>Users in Group {$groupID}</h3>" . PHP_EOL;

            foreach($groups as $group){
                $output.= "<span class='user-name'>Username: " . $group['user_id'] . ": {$group['username']},</span><br />" . PHP_EOL;
            }
            $output.= "</div>" . PHP_EOL;
        }


        var_dump($output);
        // echo $output;



        // THE var_dump($output) PRODUCES::         
        string '<div class='group1'>
                    <h3 class='group-users'>Users in Group 1</h3>
                    <span class='user-name'>Username: 1: John,</span><br />
                </div>
                <div class='group2'>
                <h3 class='group-users'>Users in Group 2</h3>
                    <span class='user-name'>Username: 2: Mark,</span><br />
                    <span class='user-name'>Username: 2: Steve,</span><br />
                </div>
                ' (length=317)

在PHP foreach循环中对项目进行分组

3 个答案: