這個SQL查詢有什麼問題？

Question

我有兩個表格：照片和photograph_tags。 Photograph_tags包含一個名爲photograph_id的列（照片中的ID）。您可以爲一張照片製作多個標籤。我有一個與三個標籤相關的照片行：男孩，小溪和水。但是，運行以下查詢返回0行

SELECT p.* 
FROM photographs p, photograph_tags c 
WHERE c.photograph_id = p.id 
AND (c.value IN ('dog', 'water', 'stream')) 
GROUP BY p.id 
HAVING COUNT(p.id)=3 

此查詢有問題嗎？

My tables look like so 
----------------------- 
photographs 
----------------------- 
id | title | location 
------------------------ 
7 | asdf | c:\... 


----------------------- 
photograph_tags 
----------------------- 
id | photograph_id | value 
1 | 7    | dog 
2 | 7    | water 
3 | 7    | stream 
4 | 7    | mountains 

I want to pull all photograph rows that relate to at least all three of the searched tags 

Answer 1

使用您指定的3個標籤（或更多）獲取所有照片。從標籤開始並加入照片。

select 
p.id 
from photographs p 

left join photograph_tags c 
on p.id = c.photograph_id 
and c.value IN ('dog', 'water', 'stream') 

group by p.id 

having count(c.value) >= 3 

測試上面的代碼：

create table #photograph_tags (
    photograph_id INT, 
    value varchar(50) 
) 

create table #photographs (
    id int 
) 

insert into #photographs values (7) 
insert into #photographs values (8) 

insert into #photograph_tags values (7, 'dog') 
insert into #photograph_tags values (7, 'water') 
insert into #photograph_tags values (7, 'stream') 
insert into #photograph_tags values (7, 'mountains') 
insert into #photograph_tags values (8, 'stream') 
insert into #photograph_tags values (8, 'mountains') 

select * from #photographs 
select * from #photograph_tags 

select 
    p.id 
from #photographs p 

left join #photograph_tags c 
on p.id = c.photograph_id 
and c.value IN ('dog', 'water', 'stream') 

group by p.id 

having count(c.value) >= 3 


drop table #photograph_tags 
drop table #photographs 

Answer 2

SELECT p.* FROM photographs p join 
(select id, COUNT(id) as TagCount 
    FROM Photograph_Tags c 
    WHERE c.value IN ('dog', 'water', 'stream') 
    group by id) 
    as TagCounts on p.id = TagCounts.id 
WHERE TagCount = 3 

Answer 3

SELECT P * FROM照片p WHERE（c.value IN（ '狗'， '水'， '流'） ） AND（SELECT COUNT（*） FROM photograph_tags c
WHERE c.photograph_id = p.id）> = 3;

會給你帶有至少三個標籤的照片。