放在哪里＆＃39;在哪里？

Question

我有以下查询：

select 
sites.denomination,
rooms.floor,
rooms.number,
(count(beds.id) - sum(if(beds.state<0,1,0))) as active
from rooms
join sites on rooms.site_id = sites.id
join beds on rooms.id = beds.room_id group by beds.room_id
order by
    sites.denomination,
    rooms.floor

它的工作非常好，但我想在网站上添加一个选项（field sites.id）。我总是得到错误：＆＃34;你的SQL语法有错误;检查手册...＆＃34;

谢谢！

Answer 1

SELECT
sites.denomination,
rooms.floor,
rooms.number,
(COUNT(beds.id) - SUM(if(beds.state<0,1,0))) AS active
FROM rooms
JOIN sites ON rooms.site_id = sites.id
JOIN beds ON rooms.id = beds.room_id 
//your WHERE should be here
GROUP BY beds.room_id
ORDER BY
    sites.denomination,
    rooms.floor

Answer 2

select 
sites.denomination,
rooms.floor,
rooms.number,
(count(beds.id) - sum(if(beds.state<0,1,0))) as active
from rooms
join sites on rooms.site_id = sites.id
join beds on rooms.id = beds.room_id 
where sites.id = ...
group by beds.room_id
order by
    sites.denomination,
    rooms.floor

Answer 3

就像这样“

select...
from...joins
where....
group by..
having.....
order by...
limit....

有关详细信息，请参阅MYSQL Docs。

所以在你的情况下就像是：

select 
sites.denomination,
rooms.floor,
rooms.number,
(count(beds.id) - sum(if(beds.state<0,1,0))) as active
from rooms
join sites on rooms.site_id = sites.id
join beds on rooms.id = beds.room_id 
where ...........//Add your where condition here
group by beds.room_id
order by
    sites.denomination,
    rooms.floor

Answer 4

试试这个：

select 
sites.denomination,
rooms.floor,
rooms.number,
(count(beds.id) - sum(if(beds.state<0,1,0))) as active
from rooms
inner join sites on rooms.site_id = sites.id
inner join beds on rooms.id = beds.room_id 
where **instruction**
group by beds.room_id
order by
sites.denomination,
rooms.floor