将两个sql连接转换为双连接？可能？

Question

我目前有两个单独的SQL JOINS。一个是获取项目名称，另一个是来自同一ID的两个不同表的类名。

一个名为PUPILPROJECT的表包含一个ID，projectID和ClassID，它们也在PROJECT表中，带有PROJECT名称和带有CLASS名称的CLASS表。

有没有办法通过单个查询执行此操作？非常感谢所有帮助！

//GET PROJECT NAME
$getproject = mysql_query("SELECT project_name FROM projects JOIN pupilproject USING     (project_id) WHERE pupil_project_id = '".$id."'");
while ($row = mysql_fetch_array($getproject)) {
$thisproject = $row['project_name'];
}

//GET PROJECT CLASS NAME
$classname = mysql_query("SELECT class_name FROM class JOIN pupilproject USING     (class_id) WHERE pupil_project_id = '".$id."'");
while ($row = mysql_fetch_array($classname)) {
$pclass = $row['class_name'];
}

Answer 1

在代码中使用以下SQL：

"SELECT project_name, class_name
FROM pupilproject
LEFT JOIN projects USING (project_id)
LEFT JOIN class USING (class_id)
WHERE pupil_project_id = '".$id."'"