在Linq中使用Distinct到SQL

Question

该查询如何从sql更改为linq？

category 
select distinct prodCategory from table4 

subcategory 
SELECT distinct [prodSubCat] FROM [table4] WHERE ([prodCategory] = @prodCategory) 


prodCategory prodSubCat 
------------------------------------- 
Home   Cassette Receiver 
Home   Receiver 
Home   cd player 
Home   cd player 
Home   Receiver 
Car    dvd player 
Car    GPS 

Ex。

我的目标是让prodSubCat为prodCategory = “驾驶”

Car    dvd player 
Car    GPS 

Answer 1

使用Distinct()

从序列MSDN

返回不同的元素。

IEnumerable<string> category = (from p in t.table4 
           select p.prodCategory).Distinct(); 

IEnumerable<string> subCategory = (from p in t.table4 
            where p.prodCategory == "Car" 
            select p.prodSubCat).Distinct(); 

Answer 2

使用Distinct - >通过使用默认的相等比较器对值进行比较返回序列中的不同元件。 （MSDN：http://msdn.microsoft.com/en-us/library/bb348436.aspx）

var results = dataContext.Table4.Where(t => t.prodCategory.Equals(prodCategory)).Distinct();