基於2個表的MySQL計數值（使用group by？）

Question

好的，太晚了，所以這也許很明顯，但是我遇到了一些麻煩。

我有2張桌子。

Filter
-

id
catId
value

所有值都應該是唯一的，因此此查詢將獲取所有值及其“ id”

select value as prodVal, id 
from Filter 
where catId = 7 group by prodVal

該查詢返回此...

id = 82, value = 'filter1'
id = 92, value = 'filter2'
etc.. etc... 

然后，我需要獲取該“ id”列表，並在第二個表上對其進行處理

prodFilters
-
id
filterId
productId

因此，我需要計算在上一個查詢中拉出的每個“ ID”在“ prodFilters”中存在多少次“ FilterID” ...

FOREACH（先前查詢的ID）做到這一點...

select count(*) from prodFilters 
where filterId = {value from last query} 
group by filterId

有什么方法可以通過一個查詢來完成所有工作，而不是先運行第一個查詢，然后再運行多個查詢？

任何幫助深表感謝。

Answer 1

您應該可以使用IN子句

SELECT filterid, COUNT(*)
FROM   prodfilters
WHERE  filterid IN (SELECT id 
                    from Filter 
                    WHERE  catid = 7 
                    group by prodVal)
GROUP  BY filterid 

Answer 2

嘗試這個：

Select f.value as prodVal, f.id,  Count(pf.filterId) as 'Filter Count'
From Filter f
inner join prodFilters pf on f.id = pf.filterId
where f.catId = 7 
group by pf.filterId

Answer 3

您是否正在尋找這樣的東西？

select Filter.value as prodVal, Filter.id , count(filterId) from prodFilters, Filter where filterId IN (select id from Filter where catId = 7) group by filterId

Answer 4

    select count(filterid) 
from prodfilters where id in (select value as prodVal, id 
    from Filter 
    where catId = 7 group by prodVal) as temp 
    group by id

Answer 5

SELECT catId, COUNT(*)
FROM   prodFilters
WHERE  catId IN (SELECT id from Filter
                    WHERE  catId = 1 )
GROUP  BY catId

Answer 6

select count(p.id) , p.filderId from prodFilters as p , filter as f
where p.filterId = f.id and f.catId = 7 
group by p.filterId

我認為這會起作用，因為每個catId，值都是唯一字段

Answer 7

您可以使用像

With A as {

select value as prodVal, id 
from Filter 
where catId = 7 group by prodVal

}
select count(*) from prodFilters 
where filterId in {A.id} 
group by filterId

這在oracle中工作正常，但不確定MySQL

MySQL的：

SELECT   COUNT (*)
    FROM prodfilters t
         JOIN
         (SELECT   VALUE AS prodval, ID
              FROM filter
             WHERE catid = 7
          GROUP BY prodval) ta ON ta.ID = t.filterid
GROUP BY filterid

Answer 8

您可以使用此查詢

select COUNT(*) from  filter as f left outer join prodFilter as p on f.Id = p.filterId