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
到现在为止还好。然而,当尝试对结果进行分组时,问题就出现了,因为我找不到映射到我在这里编写的第一个查询的LINQ to SQL查询(感谢LINQPad让这个过程变得更容易)。下面是我找到的唯一一个能给我想要的结果的:
from answer in tpoll_answer where answer.poll_nbr = 16 _
group by a_id = answer.answer_nbr into votes = count(answer.user_nbr)
这反过来又在所有SQL查询中产生了丑陋和未优化的结果:
SELECT [t1].[answer_nbr] AS [a_id], (
SELECT COUNT(*)
FROM (
SELECT CONVERT(Bit,[t2].[user_nbr]) AS [value], [t2].[answer_nbr], [t2].[poll_nbr]
FROM [TPOLL_ANSWER] AS [t2]
) AS [t3]
WHERE ([t3].[value] = 1) AND ([t1].[answer_nbr] = [t3].[answer_nbr]) AND ([t3].[poll_nbr] = @p0)
) AS [votes]
FROM (
SELECT [t0].[answer_nbr]
FROM [TPOLL_ANSWER] AS [t0]
WHERE [t0].[poll_nbr] = @p0
GROUP BY [t0].[answer_nbr]
) AS [t1]
-- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [16]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 3.5.30729.1
任何帮助都将不胜感激。
https://stackoverflow.com/questions/448203
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