我有一张表格,其中player
和skill
之间存在多对多的关系。
目标是使用单个查询列出玩家及其“前三项技能”。
create table player(
id int primary key
);
create table skill(
id int primary key,
title varchar(100)
);
create table player_skills (
id int primary key,
player_id int,
skill_id int,
value int
);
查询:
SELECT
p.id,
group_concat(s.title SEPARATOR ', ') as skills
FROM player p
LEFT JOIN player_skills ps ON ps.player_id = p.id
LEFT JOIN skill s ON s.id = ps.skill_id
WHERE ps.value > 2
-- skills limit 3 some how ...
group by p.id
order by s.id
-- expected result
-- player_ID, skills
-- 1 , 'one'
-- 2 , 'one'
-- 3 , 'two, three, four'
正如您在fiddle中所看到的,查询结果仅缺少3个技能的限制。
我尝试了多种子查询、连接等变体,但都没有效果。