[英]Entity Framework 6 query with Distinct filter
我有個問題。 當我運行以下代碼時:
var data = context.TableX.Where(w => w.userId == 9999&& w.id == 9999) .Distinct().ToList();
這是生成的查詢:
SELECT [Extent1].[id] AS [id], [Extent1].[name] AS [name], [Extent1].[companyId] AS [companyId], [Extent1].[userId] AS [userId] FROM [TableX] AS [Extent1] WHERE (9999 = [Extent1].[userId]) AND (9999= [Extent1].[id]) -- Executing at 01/06/2016 17:28:01 -03:00 -- Completed in 271 ms with result: SqlDataReader
我想知道是否可以使“ Distinct”與查詢一起運行,如下所示:
SELECT DISTINCT id, name, companyId AS type FROM TableX WHERE id=9999 AND userId=9999
謝謝。
要獲取您要查詢的查詢,您需要先調用Select
然后再調用Distinct
來僅獲取需要應用唯一字段的列:
var data = context.TableX.Where(w => w.userId == 9999&& w.id == 9999)
.Select(e=>new {e.id, e.name, e.companyId})
.Distinct()
.ToList();
我很確定第一個查詢應該可以工作,但是無論如何,另一個解決方案可以通過以下方法應用組:
var data = context.TableX.Where(w => w.userId == 9999&& w.id == 9999)
.GroupBy(e=>new {e.id, e.name, e.companyId})
.Select(g=>new{g.Key.id, g.Key.name, g.Key.companyId})
.ToList();
現在,我在另一個上下文中使用相同的思想在LinqPad中測試了第一個查詢:
var query=Agencies.Where(a=>a.StatusId==1)
.Select(e=>new{e.StateId, e.AgencyName})
.Distinct()
.Dump();
這是生成的sql:
-- Region Parameters
DECLARE @p0 Int = 1
-- EndRegion
SELECT DISTINCT [t0].[stateId] AS [StateId], [t0].[agencyName] AS [AgencyName]
FROM [Agencies] AS [t0]
WHERE [t0].[statusId] = @p0
如您所見,它應該可以工作,我真的不知道您的情況如何。
對要通過LinqPad執行的第二個查詢重復相同的過程:
var query=Agencies.Where(a=>a.StatusId==1)
.GroupBy(e=>new{e.StateId, e.AgencyName})
.Select(g=>new{g.Key.StateId, g.Key.AgencyName})
.Dump();
這是SQL代碼:
-- Region Parameters
DECLARE @p0 Int = 1
-- EndRegion
SELECT [t0].[stateId] AS [StateId], [t0].[agencyName] AS [AgencyName]
FROM [Agencies] AS [t0]
WHERE [t0].[statusId] = @p0
GROUP BY [t0].[stateId], [t0].[agencyName]
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