<form method="post" action="<?php $_SERVER['PHP_SELF']; ?>">
//使用自引用表单，$_SERVER['PHP_SELF']变量显示PHP文件自身文件名
<?php
//连接MySQL数据库
$dbc=mysqli_connect('localhost','root','root','test_store') or die('Error conneting to MySQL server.');
//判断表单是否提交过
if(isset($_POST['submit'])){
    foreach($_POST['todelete'] as $delete_id){
    //$_POST['todelete']就是todelete[]数组，被选中的复选框的值都会存在这个数组里面
        $query="delete from email_list where id=$delete_id";
        mysqli_query($dbc,$query) or die('error delete data.');
    }
    echo "email is removed.<br />";
}
//查询email_list数据表
$query="select * from email_list";
$result=mysqli_query($dbc,$query) or die('error select database.');
//生成复选框
while($row=mysqli_fetch_array($result)){
    //$result存储的是查询到的整张数据表；while每执行一次，$row数组中存储的是数据表的一行数据。    
    echo '<input type="checkbox" value="'.$row['id'].'" name="todelete[]" />';
    //注意name属性中方括号
    echo $row['email'];
    echo '<br />';
}
//关闭与数据库的连接
mysqli_close($dbc);
?>
<br />
<input type="submit" name="submit" value="submit">
</form>