LINQ分组和忽略列

Question

I'm using EF and LINQ. I have the following in my db table

branchId      Name        ItemId          CategoryId
2             Test1       1               1
5             Test1       1               1
3             Test1       1               2
2             Test2       2               1
7             Test2       2               1

I need to group by ItemId and BranchId should be ignored, so the output should be

Name  ItemId  CategoryId
Test1 1       1
Test1 1       2
Test2 2       2

Please help. thanks

Answer 1

You need to apply group by which is on multiple column, so for that you need to go for code like as below which do group by on multiple columns....

var numberGroups = from it in context.items
                   group it by new { it.ItemId,it.Name,it.CateogryID } into g
                   select new { ItemID = g.Key.ItemID, Name= g.Key.Name
                                CategoryID = g.Key.CategoryID };

Answer 2

var query = from item in context.Item
            group by item.Name,ItemId,item.CategoryId
           select item.Name,Item.Id,item.CategoryId;