同一表上的多个连接

Question

我的架构是

CREATE TABLE IF NOT EXISTS `account` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(120) NOT NULL,
   PRIMARY KEY (`id`)
 ); 

 CREATE TABLE IF NOT EXISTS `reseller_did` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `phone` int(11) NOT NULL,  
  `superadmin_id` int(11) NOT NULL DEFAULT '0',
  `reseller_id` int(11) NOT NULL DEFAULT '0',
  `admin_id` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  FOREIGN KEY (`superadmin_id`) REFERENCES account(`id`),
  FOREIGN KEY (`reseller_id`) REFERENCES account(`id`),
  FOREIGN KEY (`admin_id`) REFERENCES account(`id`)
) 

我想找到带有超级管理员、经销商、管理员名称的手机。问题是我不能在同一个 ID 上多次加入。我试过的查询

select phone,superadmin_id,reseller_id, admin_id, name from reseller_did join 
account on account.id=reseller_did.admin_id 

上面的查询通过加入 admin_id 来显示管理员名称，但是如何获取同一部手机的超级管理员名称和经销商名称？

编辑：示例输入

帐户表

id     name

3      SuperAdmin1
9      Reseller1
10     Admin1

reseller_did

id  phone        superadmin_id   reseller_id   admin_id

1   9090909090   3                 9             10

样本输出

phone        superadmin    reseller    admin

9090909090   SuperAdmin1  Reseller1   Admin1

Answer 1

试试这个；）

select r.phone, a.name as admin, re.name reseller, s.name as superadmin
from reseller_did r
join account a on a.id = r.admin_id
join account s on s.id = r.superadmin_id
join account re on re.id = r.reseller_id

SqlFiddle Result

或者

SELECT r.phone,
       MAX(CASE WHEN a.id = r.admin_id THEN a.name END) as admin,
       MAX(CASE WHEN a.id = r.reseller_id THEN a.name END) as reseller,
       MAX(CASE WHEN a.id = r.superadmin_id THEN a.name END) as superadmin
FROM reseller_did r
INNER JOIN account a 
ON a.id IN (r.admin_id, r.superadmin_id, r.reseller_id)
GROUP BY r.phone

这个sql应该感谢@sagi这个问题Get multiple values from another table by different relations。

SqlFiddle Result

Answer 2

希望这可行

select 
    rd.phone as Phone ,
    a.name as Superadmin,
    a1.name as Reseller,
    account.name as Admin
from
    reseller_did rd
        join
    account ON account.id = rd.admin_id
        join
    account a ON a.id = rd.superadmin_id
        join
    account a1 ON a1.id = rd.reseller_id

Answer 3

您可以为account 表创建三个别名，并使用reseller_did 表将它们INNER JOIN

SELECT 
R.id,
R.phone,
A1.name AS superadmin,
A2.name AS reseller,
A3.name AS admin
FROM reseller_did R
INNER JOIN account A1 ON R.superadmin_id = A1.id 
INNER JOIN account A2 ON R.reseller_id = A2.id
INNER JOIN account A3 ON R.admin_id = A3.id ;

SQL FIDDLE DEMO 1

替代方式：

如果您不想采用 INNER JOIN，可以使用以下查询获得相同的结果。

SELECT 
R.phone,
(SELECT name FROM account WHERE id = R.superadmin_id) AS SuperAdmin,
(SELECT name FROM account WHERE id = R.reseller_id) AS Reseller,
(SELECT name FROM account WHERE id = R.admin_id) AS Admin
FROM reseller_did R;

SQL FIDDLE DEMO 2

注意：您将电话号码存储在 INT 数据类型中。您不应该使用INT 来存储电话号码。相反，您应该使用VARCHAR。