Select distinct values from DataTable column asp.net

Method 1:
 
DataView view = new DataView(table);
DataTable distinctValues = view.ToTable(true, "id");


Method 2: 

You will have to create a class matching your datatable column names and then you can use the following extension method to convert Datatable to List

public static List<T> ToList<T>(this DataTable table) where T : new()
    {
        List<PropertyInfo> properties = typeof(T).GetProperties().ToList();
        List<T> result = new List<T>();

        foreach (var row in table.Rows)
        {
            var item = CreateItemFromRow<T>((DataRow)row, properties);
            result.Add(item);
        }

        return result;
    }

    private static T CreateItemFromRow<T>(DataRow row, List<PropertyInfo> properties) where T : new()
    {
        T item = new T();
        foreach (var property in properties)
        {
            if (row.Table.Columns.Contains(property.Name))
            {
                if (row[property.Name] != DBNull.Value)
                    property.SetValue(item, row[property.Name], null);
            }
        }
        return item;
    }

For Distinct Value

YourList.Select(x => x.Id).Distinct();