从两个表在mysql中创建VIEW

Question

我的邮件服务器的用户列表。 此表用于dovecot中的imap身份验证：

+-------------+------------------+-------------------+------------------+------+------+---------------------------------------+--------+---------+---------------------------+
| user_name   | domain_name      | passwd            | pwd_hash         | uid  | gid  | mailbox_basepath                      | enable | quota   | desc_rec                  |
+-------------+------------------+-------------------+------------------+------+------+---------------------------------------+--------+---------+---------------------------+
| logistic    | piduna.pp.ua     | loG-1990M         | _no_hash_passwd_ | 2000 | 2000 | /home/maildir/piduna.pp.ua/           |      1 | 2048000 | box for logistic          |
| 1c          | piduna.pp.ua     | 1c_user_1c        | _no_hash_passwd_ | 2000 | 2000 | /home/maildir/piduna.pp.ua            |      1 | 2048000 | Denisyuk V.V.             |
| admin       | piduna.pp.ua     | AAddMmM1N         | _no_hash_passwd_ | 2000 | 2000 | /home/maildir/piduna.pp.ua            |      1 | 2048000 | Admin                     |
| al.service  | piduna.pp.ua     | Alumo_Serv4321    | _no_hash_passwd_ | 2000 | 2000 | /home/maildir/piduna.pp.ua            |      1 | 2048000 | Alumo Service             |

我需要创建具有两列的表。 第一栏，all @ piduna.pp.ua。 第二列是我所有的电子邮件帐户。 在一张表中，我知道如何从user_name和domain_name进行串联。 看：

CREATE VIEW `forwardings_all_view` AS select lcase(concat(`users`.`user_name`,'@',`users`.`domain_name`)) AS `email_fqn` from `users` where (`users`.`enable` = 1)

但是，如何在VIEW中添加第二列：all@piduna.pp.ua。

像那样：

+------------------------------+-------------------------------------------------+
| email_fqn                    | source                                          | 
+------------------------------+-------------------------------------------------+
| .logistic@piduna.pp.ua       | all@piduna.pp.ua                                | 
| 1c@piduna.pp.ua              |                                                 | 
| admin@piduna.pp.ua           |                                                 |
| al.service@piduna.pp.ua      |                                                 | 

Answer 1

尝试这个：

create view first_user as
select user_name from users where enable limit 1;

create view forwardings_all_view as
select lcase(concat(a.`user_name`,'@',a.`domain_name`)) AS `email_fqn`,
  if(b.user_name is null, '', 'all@piduna.pp.ua') `source`
from `users` a
left join first_user b on a.user_name = b.user_name
where a.`enable` = 1;

小提琴