从数据库向多个地址发送电子邮件

Question

我正在尝试制作一个小联系表，在其中我可以向数据库中的多个用户发送电子邮件，我试图只选择所有电子邮件然后使用 while 循环发送给每个人，但是它是只发送到我数据库中的第一封电子邮件，而不是其余的.. 我不知道我哪里出错了

if(isset($_POST['submit'])) {
  $body= $_POST['body'];
  $subject= $_POST['subject'];
  $user = $_SESSION["name"];

  $sql = "SELECT * FROM $user";
  $result = $conn->query($sql);

  while($row = mysqli_fetch_array($result)){
      $email = $row["contact_email"];
      mail($email, $subject, $body,'From: myemail@gmail.com');
  }
}

Answer 1

假设您有以下表格：

用户

+----+-------+
| id | name  |
+----+-------+
|  1 | Boss  |
|  2 | Boris |
+----+-------+
create table users(
 id int auto_increment primary key,
 name varchar(255) not null
);

电子邮件

+---------+-----------------+
| user_id |      email      |
+---------+-----------------+
|       1 | boss1@boss.com  |
|       1 | boss2@boss.com  |
|       1 | boss3@boss.com  |
|       2 | boris1@boss.com |
|       2 | boris2@boss.com |
+---------+-----------------+

create table emails(
 user_id int references users(id),
 email varchar(255) not null
);

注意user_id 对users 表的引用。

现在在 PHP 中

if(isset($_POST['submit'])) {
  $body = $_POST['body'];
  $subject = $_POST['subject'];
  $user = mysqli::real_escape_string($_SESSION["name"]);

  $result = $conn->query("SELECT id from users where name='".$user."'");
  $row = mysqli_fetch_array($result);
  $user_id = intval($row["id"]);

  $sql = "SELECT email FROM emails where user_id=".$user_id;
  $result = $conn->query($sql);

  while($row = mysqli_fetch_array($result)){
      $email = $row["email"];
      mail($email, $subject, $body,'From: myemail@gmail.com');
  }
}