我想通过 P_id 选择所有类别，并加入数据表 现在其他想要 p_id 每行从数据表
中选择三行类别表
id | p_id | cat_name ----+-------+------------------------ 1 | 1 | Bookenter code here 2 | 1 | Music 3 | 1 | Game 4 | 1 | Apps
数据表
===================================== id | cat_id | data ----+-----------+-------------------- 1 | 1 | Book Data ... ... 2 | 1 | Book Data ... ... 3 | 1 | Book Data ... ... 4 | 1 | Book Data ... ... 5 | 1 | Book Data ... ... 6 | 1 | Book Data ... ... 7 | 1 | Book Data ... ... ... More ... More ... More ...
我想要这样每行cat_table data_table 3行选择
============================================================ cat_name | data ----------+-------------------------- Book | Book Data ... ... Book | Book Data ... ... Book | Book Data ... ... ------------------------------------- Music | Music Data ... ... Music | Music Data ... ... Music | Music Data ... ... ------------------------------------- Game | Game Data ... ... Game | Game Data ... ... Game | Game Data ... ... ... More ... More ... More ...
我想要这个（或）{group_concat}
========================================= cat_name | data ----------+------------------------------------------------------------ Book | Book Data ... ... | Book Data ... ... | Book Data ... ... Music | Music Data ... ... | Music Data ... ...| Music Data ... ... Game | Game Data ... ... | Game Data ... ... | Game Data ... ... ... More ... More ... More ...
我想选择所有类别按 P_id 并加入数据表现在其他想要 p_id 每行从中选择三个行数据表
任何人都可以帮助我
答案 0 :(得分：2)
希望这能解决您的问题
SELECT
sq.category,
sq.data
FROM (
SELECT
DATA.*,
cats.name AS category,
row_number() over(PARTITION BY cat_id ORDER BY cat_id DESC) AS ROW_COUNT FROM `data`
INNER JOIN cats ON data.cat_id = cats.id
) AS sq
WHERE
ROW_COUNT <= 3
在查询中...... ROW_COUNT <= 3您可以设置选择限制。