distinct values in linq

Question

I try linq query

<asp:DropDownList ID="regiondrop" runat="server" AutoPostBack="True" 
onselectedindexchanged="regiondrop_SelectedIndexChanged">
</asp:DropDownList>

I try to show distinct values in drop-down on page load. I try this query to get values

T1 tea = new T1();
var list1 = tea.t1.ToList();
var list = (from ta in list1
orderby ta.Region
select new { ta.Region,ta.RegionID }).Distinct().ToList();

but this shows all same values where as i want distinct values

update

in my scenario data is

RID  Region 
1   Paris   
2   Canada  
3   UK  
4   Paris   
5   Canada 
6   London

so in this Canada and Paris 2 times so i want this 1 time in drop-down

any solution?

What type is `Region`? You're also not showing that you are using `list` as datasource for the `DropDownList`. — Tim Schmelter, Jun 21 '16 at 09:48

score 1 · Accepted Answer · answered Jun 22 '16 at 11:45

Check this

var list1 = tea.t1
            .GroupBy(i => i.Region)
            .Select(i => new 
            {
                RegionID = i.Min(t => t.RegionID) // Or Max what you want
                Region = i.Key,                 
            })
            .OrderBy(i => i.Region).ToList();

score 0 · Answer 2 · edited May 23 '17 at 12:08

0

If you want to get values distinct by a property -like Region- you can use GroupBy function.

T1 tea = new T1();
var list1 = tea.t1.ToList();
var list = (from ta in list1
        orderby ta.Region
        select new { ta.Region, ta.RegionID })
        .GroupBy(g=>g.Region)
        .Select(g=>g.First())
        .ToList();

For an extension method : LINQ: Distinct values

edited May 23 '17 at 12:08

Community

1
1

answered Jun 21 '16 at 09:58

Cihan Yakar

2,402
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in my scenario.. data is .. `RID Region 1 Paris 2 Canda 3 UK 4 Paris 5 Canda 6 London ` now in this canada and paris appear 2 times so i want this 1 time in dropdown – SUPER_USER Jun 22 '16 at 04:23
this solution not work . when i try this data displayed in dropdown multiple times ...check update please – SUPER_USER Jun 22 '16 at 04:25
Then group by `Region` instead `RegionId`. I edited sample code. – Cihan Yakar Jun 22 '16 at 11:35

distinct values in linq

2 Answers2