PL/SQL发送带附件的电子邮件？

CREATE OR REPLACE PROCEDURE send_email_with_attachment (
   p_to          IN  VARCHAR2,
   p_subject     IN  VARCHAR2,
   p_message     IN  VARCHAR2,
   p_attachment  IN  BLOB
)
AS
   l_mail_conn   UTL_SMTP.connection;
   l_boundary    VARCHAR2(50) := '----=*#abcdefg1234567890';
BEGIN
   l_mail_conn := UTL_SMTP.open_connection('your_smtp_server', 25);
   UTL_SMTP.helo(l_mail_conn, 'your_smtp_server');
   UTL_SMTP.mail(l_mail_conn, 'your_email@example.com');
   UTL_SMTP.rcpt(l_mail_conn, p_to);

   UTL_SMTP.open_data(l_mail_conn);

   UTL_SMTP.write_data(l_mail_conn, 'From: your_email@example.com' || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, 'To: ' || p_to || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, 'Subject: ' || p_subject || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, 'MIME-Version: 1.0' || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, 'Content-Type: multipart/mixed; boundary="' || l_boundary || '"' || UTL_TCP.crlf || UTL_TCP.crlf);

   -- 发送邮件正文
   UTL_SMTP.write_data(l_mail_conn, '--' || l_boundary || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, 'Content-Type: text/plain; charset="iso-8859-1"' || UTL_TCP.crlf || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, p_message || UTL_TCP.crlf);

   -- 发送附件
   UTL_SMTP.write_data(l_mail_conn, '--' || l_boundary || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, 'Content-Type: application/octet-stream' || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, 'Content-Disposition: attachment; filename="attachment.txt"' || UTL_TCP.crlf || UTL_TCP.crlf);
   UTL_SMTP.write_data(l_mail_conn, p_attachment);
   UTL_SMTP.write_data(l_mail_conn, UTL_TCP.crlf);

   -- 结束邮件
   UTL_SMTP.write_data(l_mail_conn, '--' || l_boundary || '--' || UTL_TCP.crlf);
   UTL_SMTP.close_data(l_mail_conn);

   UTL_SMTP.quit(l_mail_conn);
END;

DECLARE
   l_attachment  BLOB;
BEGIN
   SELECT utl_raw.cast_to_raw('This is the attachment content.') INTO l_attachment FROM dual;
   send_email_with_attachment('recipient@example.com', 'Test email with attachment', 'This is the email message.', l_attachment);
END;