我有3个表的数据库，如：
服务
id | name | service_id (UNIQUE)
1 | new | 123
2 | service1 | 543
计数
id | counts | counts_price | service_id
1 | 100 | 200 | 123
5 | 200 | 250 | 123
6 | 300 | 350 | 543
背景
id | background | background_price | service_id
1 | white | 50 | 123
12 | red | 150 | 123
我的查询如下：
Eff：service_id = 123
在输出中我得到了
var_dump
为什么它重复？查询有什么问题？
SELECT background.background, services.name, counts.count
FROM services INNER JOIN background
ON background.service_id=services.service_id INNER JOIN counts
ON counts.service_id=services.service_id
WHERE services.service_id = :service_id
答案 0 :(得分：1)
为此添加group by。
GROUP BY services.service_id
所以你的最终查询是：
SELECT background.background, services.name, counts.count, services.service_id
FROM services INNER JOIN background
ON background.service_id=services.service_id INNER JOIN counts
ON counts.service_id=services.service_id
WHERE services.service_id = :service_id
GROUP BY services.service_id
答案 1 :(得分：0)
我认为您的问题是您的数据不知道哪些背景与哪些背景相关联。在这个简单的例子中，你可以生成行号以帮助这样的事情 -
select t.background
,se.name
,s.counts_price
from
(
select c.*,
if(c.service_id<> @p, @rn:=1,@rn:=@rn+1) rownumber,
@p:=c.service_id p
from (select @rn:=0,@p:=0) rn,counts c
order by c.service_id,c.id
) s
join
(
select b.*,
if(b.service_id<> @p1, @rn1:=1,@rn1:=@rn1+1) rownumber1,
@p1:=b.service_id p
from (select @rn1:=0,@p1:=0) rn,background b
order by b.service_id,b.id
) t on t.service_id = s.service_id and t.rownumber1 = s.rownumber
join services se on se.service_id = s.service_id
结果
+------------+------+--------------+
| background | name | counts_price |
+------------+------+--------------+
| white | new | 200 |
| red | new | 250 |
+------------+------+--------------+
答案 2 :(得分：0)
根据你的输出
SELECT background.background, services.name, counts.count
FROM services INNER JOIN background
ON background.service_id=services.service_id INNER JOIN counts
ON counts.service_id=background.service_id AND counts.id != background.id
WHERE services.service_id = 123
希望它能够满足您的需求