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POLINQ to SQL using GROUP BY and COUNT(DISTINCT)
 

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  1. POLINQ to SQL using GROUP BY and COUNT(DISTINCT)
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    <p>I have to perform the following SQL query:</p> <pre><code>select answer_nbr, count(distinct user_nbr) from tpoll_answer where poll_nbr = 16 group by answer_nbr </code></pre> <p>The LINQ to SQL query </p> <pre><code>from a in tpoll_answer where a.poll_nbr = 16 select a.answer_nbr, a.user_nbr distinct </code></pre> <p>maps to the following SQL query:</p> <pre><code>select distinct answer_nbr, distinct user_nbr from tpoll_answer where poll_nbr = 16 </code></pre> <p>So far, so good. However the problem raises when trying to GROUP the results, as I'm not being able to find a LINQ to SQL query that maps to the first query I wrote here (thank you <a href="http://www.linqpad.net/" rel="noreferrer">LINQPad</a> for making this process a lot easier). The following is the only one that I've found that gives me the desired result:</p> <pre><code>from answer in tpoll_answer where answer.poll_nbr = 16 _ group by a_id = answer.answer_nbr into votes = count(answer.user_nbr) </code></pre> <p>Which in turns produces the follwing ugly and non-optimized at all SQL query:</p> <pre><code>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 </code></pre> <p>Any help will be more than appreciated.</p>
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