How to implement multi-level associated multi-dimensional arrays in PHP and Mysql?

Question

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As shown in the figure, a User has multiple topics, and each topic has a corresponding theme.

Please tell me how to implement this relationship using php+mysql?

Answer 1

Do you mean the actual table structure, or how to query this data form

I don’t know if you wrote it in a framework or natively

// 查詢USER表
$returndata = array();
while($userdata = mysql_fetch_assoc()) {
   
    $id = $userdata['id'];
    //跟著根據id查詢topics
    $topicssql = "";
    .....
    $userdata['topics'] = array();
    while($topicsd = mysql_fetch_assoc()) {
        $userdata['topics'][] = $topicsd; 
    }
}

Answer 2

This is usually done by merging the retrieved data in the background