如何根据条件从多个表中 select

Question

我有两个table：

post table:

+-----+------------+--------------+
| id  |   title    |   details    |
+-----+------------+--------------+
| 185 | some title | some details |
| 186 | some title | some details |
+-----+------------+--------------+

post 类别：

+----+------------+---------+
| id |  category  | post_id |
+----+------------+---------+
|  1 | some title |     185 |
|  2 | some title |     186 |
+----+------------+---------+

当用户点击类别时，我想根据类别 selected.

从 post table 中获取所有 posts

我可以 select category 和 post_id 像这样：

List<Map> postCategories2 = Base.findAll("select category, post_id from posts_categories where category = ?", request.queryParams("category_name"));

但我想要的是使用单个查询和 select id, title, details 来自 post table 使用 category and post_id 来自 table 2 即 category table

我拥有的所有信息都是类别名称，即 request.queryParams("category_name")

注：id and post_id有主键-外键关系

Answer 1

我认为你必须为此使用连接用这个查询替换你的查询

select title,details,category from post p inner join posts_categories c on 
 p.id=c.post_id where category= ?//your category name at the question mark

希望这对您有所帮助

如何根据条件从多个表中 select

How to select from multiple tables based on condition

java

sql

activejdbc

javalite