合并两个SELECT查询 [英] merging two SELECT queries

问题描述

我要么变老，要么我需要编写的查询变得越来越复杂.以下查询将获取与用户关联的所有tasks.

I am either getting old or the queries that I need to write are getting more and more complicated. The following query will get all the tasks associated with the user.

"SELECT `date` 
   FROM `tasks` 
  WHERE `user_id`= 1;"

tasks表为(id，date，user_id，url_id);

现在，我还需要获取url_id与用户通过

Now, I need to get as well records that url_id associates with the user trough the

`urls` table (`id`, `user_id`)

独立查询如下:

"SELECT `t1`.`data` 
   FROM `tasks` `t1` 
   JOIN `urls` `u1` ON `u1`.`id` = `t1`.`url_id` 
  WHERE `u1`.user_id` = 1;"

但是，是否可以将这两个查询合并为一个查询?我的逻辑是应该这样，尽管我不知道如何进行实际的JOIN.

Though, is it possible to merge these two queries into a single query? My logic says it should be, though I don't see how to do the actual JOIN.

推荐答案

我可能会使用联盟.

SELECT `date`
   FROM `tasks` WHERE `user_id`=1
UNION
SELECT `t1`.`date`
   FROM `tasks` `t1`
   INNER JOIN `urls` `u1` ON `u1`.`id` = `t1`.`url_id`
   WHERE `u1`.user_id`=1;

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