Question

我的问题是我需要通过一个查询从不同的表中获取数据（电子邮件）。我搜索过，找不到足够的信息，所以我决定在这里问一下。

我们的想法是向不同部门的某些人发送电子邮件，并将电子邮件发送给所有部门的每个人。我的代码如下;

if ($_POST['recipient'] == 'parents'){$query = "SELECT `email`, `first_name` FROM `users` WHERE `allow_email` = 1 AND `active` = 1";}
        if ($_POST['recipient'] == 'teachers'){$query = "SELECT `email`, `name` FROM `teachers` WHERE `status` = 1";}
        if ($_POST['recipient'] == 'staff'){$query = "SELECT `email`, `name` FROM `staff`";}


        $result = $con->query($query);
        while ($row = $result->fetch_array(MYSQLI_ASSOC)) {

            $mail = new PHPMailer();
            $mail->IsHTML(true);
            $mail->SMTPAuth   = true;                  // enable SMTP authentication
            $mail->Host       = $site_settings['smtp_host']; // sets the SMTP server
            $mail->Port       = 26;                    // set the SMTP port
            $mail->Username   = $site_settings['smtp_username']; // SMTP account username
            $mail->Password   = $site_settings['smtp_password']; // SMTP account password
            $email->From      = $site_settings['school_email'];
            $email->FromName  = $site_settings['school_name'];
            $email->Subject   = 'Newsletter: '.$_POST['subject'];
            $email->Body      = $_POST['body'];
            $email->AddAddress( $row['email'] );

            $email->Send(); 
        }

有人可以帮忙吗？

Answer 1

您可以在三个表之间使用UNION来获取一个结果集。查询将如下所示：

SELECT `email`, `first_name`, 'user' FROM `users` WHERE `allow_email` = 1 AND `active` = 1
UNION
SELECT `email`, `name`, 'teacher' FROM `teachers` WHERE `status` = 1
UNION
SELECT `email`, `name`, 'staff' FROM `staff`

您的PHP代码可能如下所示：

if ($_POST['recipient'] == 'parents'){$query = "SELECT `email`, `first_name` FROM `users` WHERE `allow_email` = 1 AND `active` = 1";}
elseif ($_POST['recipient'] == 'teachers'){$query = "SELECT `email`, `name` FROM `teachers` WHERE `status` = 1";}
elseif ($_POST['recipient'] == 'staff'){$query = "SELECT `email`, `name` FROM `staff`";}
elseif ($_POST['recipient'] == 'all')($query="SELECT `email`, `first_name`, 'user' FROM `users` WHERE `allow_email` = 1 AND `active` = 1 UNION SELECT `email`, `name`, 'teacher' FROM `teachers` WHERE `status` = 1 UNION SELECT `email`, `name`, 'staff' FROM `staff`")

查询中的列名称将是UNION的第一个SELECT中的列名，因此要访问包含＆＃39; teacher＆＃39;，＆＃39; staff＆＃39;或者＆＃39;用户＆＃39;您会使用$row['user']，如果您想在代码中使用此人的姓名，则可以使用$row['first_name']，而不是$row['name']，但您可以通过以下方式更改从以下开始：

SELECT `email`, `first_name` as name, 'user' as type FROM `users` ...

如何使用一个查询从3个不同的mysql表中获取数据

1 个答案: