Question

好吧，它已经很晚了，所以这可能很明显，但我遇到了一些麻烦。

我有2张桌子。

Filter
-

id
catId
value

所有值都应该是唯一的，以便此查询获取所有值及其“id”s

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

该查询返回此...

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

然后我需要获取“id”列表并在第二个表上处理它，即

prodFilters
-
id
filterId
productId

所以我需要计算“prodFilters”中出现的“FilterID”在前一个查询中提取的每个“ID”中出现的次数......

FOREACH（上次查询的ID）DO THIS ...

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

有没有办法通过一个查询完成所有这些，而不是运行第一个查询然后再运行多个查询？

非常感谢任何帮助。

Answer 1

您应该能够使用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

试试这个：

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

你正在寻找这样的东西吗？

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

我认为这样可行，因为每个catId值都是唯一字段

Answer 7

您可以使用

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

这在oracle中运行良好，但对MySQL不确定

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

您可以使用此查询

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

MySQL计数值（使用group by？）基于2个表

8 个答案: