Question

以下是我正在运行的查询，以获取给定对象的每个键的每个值的计数：

SELECT key, value, COUNT(value)
FROM keyval kv
WHERE object_id = 123456
GROUP BY kv.key, kv.value
ORDER BY kv.key, kv.value;

我查询的表非常简单。它只是：

object_id BIGINT
key       VARCHAR(45)
value     VARCHAR(45)

所以我得到的价值如下：

Color    Red     26
Color    Blue    24
Shape    Circle  14
Shape    Square  12

所以我想解析Blue和Square的结果，但保留Red和Circle的结果。这可能吗？

Answer 1

我会在子查询或cte：

中使用row_number

select
    [key],
    value,
    cnt
from (
     select
         [key],
         value,
         count(*) as cnt,
         row_number() over(partition by [key] order by count(*) desc) rnk
     from keyval
     where object_id = 123456
     group by
         [key],
         value
     ) kv
where rnk = 1

http://sqlfiddle.com/#!6/4d869/5

Answer 2

试试这个，但要注意红色和蓝色都有26个数字的情况......两者都会被退回。

with cte as
    (select k,v,count(v) c
    from #kvp
    group by k,v)
select results.* 
from 
    cte restults
    inner join (select k, max(c) m from cte group by k) filter
        on restults.k = filter.k
where 
    filter.m = restults.c
    and id = @id

Answer 3

试试这个。

SELECT KEY,
       value,
       Max(cnt)
FROM  (SELECT KEY,value,Count(value) As cnt
       FROM   keyval kv
       WHERE  object_id = 123456
       GROUP  BY kv.KEY,kv.value
       ORDER  BY kv.KEY Desc,kv.value Desc
       ) a
GROUP  BY a.KEY

是否可以在一个查询中为表中的每个键最多出现一个值？

3 个答案: