sql – 如何将具有相同字段的两个表的结果连接到一个字段中？

我有这样的表：

   Table1                Table2
   name1 | link_id      name2  |  link_id
   text       1         text         2
   text       2         text         4

我想得到结果：

name1     name2     link_id
text      text         1
text      text         2
text      text         4

我怎么能这样做？

加：
Sry,我的英语不太好.我有设备,device_model和device_type表与重复字段counter_set_id.我想从counter_set中选择具有counter_set_id的所有值的字段.我只需要从counter_set_id字段中获取值

现在我有这个查询：

SELECT  `dev`.`counter_set_id`,`mod`.`counter_set_id`,`type`.`counter_set_id`
FROM    `device` AS `dev`
LEFT JOIN   `device_model` AS `mod` ON `dev`.`device_model_id` = `mod`.`id`
LEFT JOIN   `device_type` AS `type` ON `mod`.`device_type_id` = `type`.`id`
WHERE   `dev`.`id` = 4;

这将返回3列,但我需要一列中的所有值

这是我认为的最终变体：

SELECT  `dev`.`counter_set_id`
FROM        `device` AS `dev` LEFT OUTER JOIN
        `device_model` AS `mod` ON `dev`.`device_model_id` = `mod`.`id`
WHERE   `dev`.`id` = 4 AND
        `dev`.`counter_set_id` IS NOT NULL
UNION
SELECT  `mod`.`counter_set_id`
FROM        `device_model` AS `mod` LEFT OUTER JOIN
        `device` AS `dev` ON `mod`.`id` = `dev`.`device_model_id`
WHERE   `mod`.`counter_set_id` IS NOT NULL;

最佳答案

根据您提供的样本表和所需的输出,听起来您可能想要一个完整的外部联接.并非所有供应商都实现了这一点,但您可以使用LEFT OUTER连接和UNION到EXCEPTION连接来模拟它,其中表格反转如下：

Select name1,name2,A.link_id
From table1 A Left Outer Join
     table2 B on A.link_id = B.link_id
Union
Select name1,link_id
From table2 C Exception Join
     table1 D on C.link_id = D.link_id

然后你的输出将是这样的：

NAME1   NAME2    LINK_ID
=====   =====    =======
text