在 foreach 中处理 codeigniter php array_merge 的最佳方法是什么？

Question

我正在尝试列出来自 school_location_id = 1 的学校的所有学生，我使用 codeigniter 的USE连接到多个学校数据库。 我的挑战是它只列出最后一所学校的学生。 下面是我的代码，

$schools = $this -> db->select('*')
    ->from('schools')
    ->where('schools.school_location_id', 1)
    ->get()->result_array();
foreach ($schools as $row) :
    $school_db_name = $row['school_db_name'];
    $this->db->query("use $school_db_name");  // here I switch school database, cause I'm connected to multiple school databasees
    $school_students = $this->db->select('*')
        ->from('school_students')
        ->get()->result_array();
endforeach;

$recipients = array_merge($school_students);

foreach ($recipients as $row) :
    echo $row['name'];
endforeach;

Answer 1

$school_students正在为您的 foreach 循环的每一次通过而被覆盖。 一种替代方法是简单地将结果添加到数组中，如下所示：

    foreach($schools as $row):
            $school_db_name    =   $row['school_db_name'];
            $this->db->query("use $school_db_name");
            $school_students[]    =   $this->db->select('*')
                                    ->from('school_students')
                                    ->get()->result_array();
    endforeach;

如果您之后需要展平数组，例如可以使用以下命令：

$recipients = array_merge(...$school_students)