SQL到LINQ條款

Question

我想在C＃中使用LINQ編寫以下SQL查詢，獲得相同結果的最佳方法是什麼？

SELECT [t1].[JOB] 
FROM (
    SELECT COUNT(*) AS [value], [t0].[JOB], [t0].[LINK], [t0].[PREFIX] 
    FROM [dbo].[LABELS] AS [t0] 
    GROUP BY [t0].[JOB], [t0].[LINK], [t0].[PREFIX] 
    HAVING [t0].[PREFIX] = 'B' AND [t0].[LINK] != 0 
    ) AS [t1] 
GROUP BY [t1].[JOB], [t1].[value] 
HAVING [t1].[value] > 1 

標籤在字段JOB和LINK上應該是唯一的，組合不應該重複。這個查詢是檢查哪些作業打破該規則

編輯：我的LINQ到目前爲止，它不會產生預期的結果。

dbP.PackagingLabels.GroupBy(l => new {l.JOB, l.LINK, l.PREFIX}) 
    .Where(g => g.Select(e => e.PREFIX != "B" && e.LINK != 0).Count() > 1) 
    .Select(g => g.Key.JOB); 

Answer 1

它看起來像你可以簡化這個大大：

SELECT COUNT(*) AS [counts], [t0].[JOB], [t0].[LINK] 
FROM [dbo].[LABELS] AS [t0] 
WHERE [t0].[PREFIX] = 'B' AND [t0].[LINK] != 0 
GROUP BY [t0].[JOB], [t0].[LINK] 
HAVING COUNT(*) > 1 

再次就像你的SQL查詢，您的LINQ應首先應用WHERE子句：

var groupsOfDupes = dbP.PackagingLabels 
    .Where(e => e.PREFIX != "B" && e.LINK != 0) 
    .GroupBy(l => new {l.JOB, l.LINK}) 
    .Where(grp => grp.Skip(1).Any()) //this returns true if there is more than one item in the group 
    .ToList(); 

這會給你一個組的列表。注意列表中的每個項目本身就是一個列表。內部列表是共享相同JOB和LINK的項目。

foreach(var group in groupsOfDupes) 
{ 
    Console.WriteLine("This combination has count > 1: { JOB: '" + group.Key.JOB + "', LINK: '" + group.Key.LINK + "' } with count of: " + group.Count()); 
}