Grouping with Data Entities

-
I am really loving the data entity in my new projects but have come across a couple of issues already. Tonight I learned about using a field that is not a part of your database and not in the entity but is a consolidation field from a group.  Once I found some good samples it worked incredibly well and I had a little summary grid on the page in just a couple of minutes.  So here is what I did

 using (myEntityName context = new myEntityName())

    {
//First I declared a couple of variables because I was looking at data between specific dates
         DateTime startdate = DateTime.Parse("2014-02-01");
            DateTime enddate = DateTime.Parse("2014-02-01");
         var dbRecords = (from c in context.myTableName
                          where (c.MemberStartDate >= startdate && c.MemberStartDate <= enddate)
                          group c by c.Concept into g
  //So you notice I used a g for the group by set of data
//The g.key part threw me for a second but then I realized it equates to the field you are grouping by
                        select new
                                     {
                                         Concept = g.Key,
                                       New_Customers_Count= g.Count()
                                     }).ToList();
     
        WebDataCustCount.DataSource = dbRecords;
        WebDataCustCount.DataBind();

Comments

Post a Comment

Popular posts from this blog

Linq Exclude from separate list

-
 var urlList = new List<DisplayAssets>();    var assetsToExclude = (from a in db.DisplayAssets                 join h in db.Hardware_Assets on a.id equals h.displayId                 where h.assetId == hardwareid                 select a.id); var allAssets = db.DisplayAssets; var urls = allAssets.Where(x => !assetsToExclude.Contains(x.id));         urlList = urls.Select(a => new DisplayAssets()         {             locaterAddress  = a.locaterAddress,             assetType = a.assetType,             id = a.id         })         .ToList();
Read more

Sorting Ascending and Descending

-
Toggling the direction of your datagrid sort is easy using a session to remember which direction you sorted last.   You will want to declare an empty string in the top of your page       Dim SortField As String Then on your sort command add this logic - Example of entire command Private Sub dgTaskExceptions_SortCommand( ByVal source As Object , ByVal e As System.Web.UI.WebControls.DataGridSortCommandEventArgs) Handles dgTaskExceptions.SortCommand     SortField = e.SortExpression If Session( "toggle" ) = True Then SortField += " DESC" Session( "toggle" ) = False Else SortField += " Asc" Session( "toggle" ) = True End If Dim orderstring As String = SortField 'REBIND dgTaskExceptions.DataSource = POTracking_Data.tracking.getSampleTasks(orderstring) dgTaskExceptions.DataBind() End Sub   In my datalayer I add this logic to my query and pass in an OPTIONAL value Dim orderbyString As String = String .Empt
Read more

Linq Query Syntax vs Method Syntax

-
Referenced from MSDN: https://msdn.microsoft.com/en-us/library/bb397947.aspx Query syntax: IEnumerable<int> numQuery1 =               from num in numbers             where num % 2 == 0             orderby num             select num; Method syntax:         IEnumerable<int> numQuery2 = numbers.Where(num => num % 2 == 0).OrderBy(n => n)
Read more