相关疑难解决方法(0)

我必须执行以下SQL查询:

select answer_nbr, count(distinct user_nbr)
from tpoll_answer
where poll_nbr = 16
group by answer_nbr

LINQ to SQL查询

from a in tpoll_answer 
where a.poll_nbr = 16 select a.answer_nbr, a.user_nbr distinct 

映射到以下SQL查询:

select distinct answer_nbr, distinct user_nbr
from tpoll_answer
where poll_nbr = 16

到现在为止还挺好.但是在尝试GROUP结果时问题就出现了,因为我无法找到映射到我在这里写的第一个查询的LINQ to SQL查询(感谢LINQPad让这个过程变得更容易).以下是我发现的唯一一个给我预期结果的:

from answer in tpoll_answer where answer.poll_nbr = 16 _
group by a_id = answer.answer_nbr into votes = count(answer.user_nbr)

这反过来会产生所有SQL查询中的丑陋和非优化:

SELECT [t1].[answer_nbr] AS [a_id], (
    SELECT COUNT(*)
    FROM (
        SELECT CONVERT(Bit,[t2].[user_nbr]) AS [value], [t2].[answer_nbr], [t2].[poll_nbr] …