Sorting DataTable String Column, But With Null/empty At The Bottom?

Mar 5, 2009

I need to sort a DataTable or DataGridView by a column that is a string value, but with null/empty values at the BOTTOM when sorting ASCENDING.The DataTable is NOT populated by a SQL statement, so no order by.If I doDataGridView1.Sort(New RowComparer(System.ComponentModel.ListSortDirection.Ascending))then it throws an exception, saying that the DataGridView is DataBound, which is correct, but doesn't help me, and I want to keep it databound.

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C# - Sorting DataTable String Column But With Null / Empty At The Bottom

Feb 7, 2011

I need to sort a DataTable or DataGridView by a column that is a string value, but with null/empty values at the BOTTOM when sorting ASCENDING. The DataTable is NOT populated by a SQL statement, so no order by. If I do

[Code]...

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Nothing Equals String.Empty, Null Does Not Equal String.Empty?

Jun 28, 2010

This must've have been asked before but I couldn't locate it. In a mixed code project (VB and C#) we were debugging some old Visual Basic code where a statement as follows could be found:

If Request.Params("xxx") <> "" Then
'do something

I considered this a bug as Request.Params could be null, in which case the statement would've become false which wasn't the idea. So I thought. I just found out, -- probably for the tenth time and I will keep forgetting -- that the following two statements are not equal, while Nothing in VB should be equal to null in C# (thought I):

if(String.Empty == null) // always false
If String.Empty = Nothing Then ' always true

Should I dismiss this as a typical Microsoft backward compatibility effort, or should I consider this a huge error in the VB.NET compiler? Does anybody know the Microsoftean opinion on this oddity?

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Asp.net Mvc - Sorting Datatable With Linq With Correct Datatype Of A Column?

Mar 27, 2012

I have this code that use to sort a datatable.

Dim sortingIndex As Integer = orderby
Dim DataTableNew As DataTable = New DataTable
DataTableNew = dt.Clone
Dim query = (From c In dt.AsEnumerable Order By c.Field(Of String)(sortingIndex) Ascending)
query.CopyToDataTable(DataTableNew, LoadOption.OverwriteChanges)

My problem is that with this method I always need (Of String) for it to work, so the date columns are also managed as Strings witch is the problem. Is there a way to use the correct type so the sorting is based on the type of the column?

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Add A Null Column To A Row In A Typed Datatable's Addrow Method?

Jul 14, 2010

vb.net 2005

Here is one attempt:

Dim myRow As BurnerService.OEBSContractBatchesRow
Dim myDate As Nullable(Of DateTime)
myRow = Me.BurnerService.OEBSContractBatches.AddOEBSContractBatchesRow( _

[Code].....

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Check Object's Property For Null Or Empty String?

Jul 28, 2009

I'm using FileHelper to generate object's property. Here is an example of one property:

<FieldOptional(), _
FieldTrim(TrimMode.Both)> _
<FieldNullValue(GetType(String), " ")> _
Public StoreNo As String

As you can see the StoreNo will either have a value or " ", one of the business policy is to check if the StoreNo is empty or nothing if the object's StoreNo is empty or null then the record will not create.

I though about creating an HasValue Function in the class to check the StoreNo and other properties in the object but I feel like it is a hack.

Public Function HasValue() As Boolean
Dim _HasValue As Boolean = True
If StringHelper.IsNullOrBlank(Me.StoreNo) Then

[Code]....

I don't think this approach is an ideal solution. what if the StoreNo is remove or change to something else. What's the best approach to check object's property?

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Inserting Empty String Field As Null In Access?

Jan 4, 2012

I have a couple of textfields in a Windows form. One of these textfields is allowed to be NULL. When I enter a value for every field, it is all inserted, no problem. When I leave the field (txtGewicht) blank, I can't seem to be able to insert NULL in Access Database.

If Double.TryParse(txtGewicht.Text, 0) Then
klant.Gewicht = Double.Parse(txtGewicht.Text)
Else

[Code]....

This is what I get:

"Cannot set column 'Gewicht' to NULL, please use DBNull instead"

So I changed 'Nothing' to DBNull.value, but it then tells me that System.DBNull cannot be converted to type Double.

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Combo Box Selected Item Is Null - Assign An Empty String To It Instead?

Dec 9, 2011

I have a property called ReplacementTo and I set a value to it based on the selecteditem from the combobox, like this:

classEquipmentItem.ReplacementTo = cmbReplcmnt.SelectedItem.ToString

Now I can't use cmbReplcmnt.Text because what I actually need is the value of that SelectedItem

So problem is, if the user leaves the combobox as blank, it throws a null exception.I decided to use the IIf function then:classEquipmentItem.ReplacementTo = IIf(IsNothing(cmbReplcmnt.SelectedItem.ToString), classEquipmentItem.ReplacementTo = "", cmbReplcmnt.SelectedItem.ToString)

Unfortunately I still get the error I tried using a Try-Catch for it and it worked, but I don't want to rely on the Try-Catch, so I was wondering is there a another way to work this through?

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C# - Reset The First Match Row's Column Value To Empty String?

Dec 11, 2009

new with Linq and very excited with this feature. However, I want to see if I can do the following with LINQ:

[code]...

Notice that I have a break in my foreach loop, meaning that I just need to reset the first match row's column value to empty string.

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String Contains Reference To DataTable.Column

Nov 8, 2011

I am using VB.NET and ADO 4.0. Given that I have a string containing a reference to a table.column, can I use the content of the string in a command? [code] I got to the point where I can use the string contents as "reference", it seemed to obvious but [strName] does the trick, partially.When I debug bookableday.room1 remains 0 whilst it should show 6. There might be a conversion issue because the debugger shows me "6" i.s.o. 6 . this is the actual code: [code]

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VS 2010 Get A Column Value From A Datatable As A String

Mar 24, 2011

I have a database (access) and a listbox which is databound to it etc, and controls the currently selected row in the database.

And i want to check a columns value from the selected row via code, how can i do it? None of the examples on google are recent or for vb.

The column i want to get the value from is

Coulmn name = Related
Column number = 15

The value will be used in a filter so needs to be returned as a string

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Excel Sorting Is Only Sorting One Column Not Multiple?

Mar 12, 2012

I'm having my program sort an excel sheet by a few columns. However, it is only sorting by the first column not the rest that I specify.ere is my sort code below:

myRange.Sort(Key1:=myRange.Range("A:A"), Order1:=XlSortOrder.xlAscending, Key2:=myRange.Range("G:G"), Order2:=XlSortOrder.xlAscending, Header:=XlYesNoGuess.xlYes, Orientation:=XlSortOrientation.xlSortColumns)

[code]...

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Test If A String Exists In A Column In A DataTable?

Sep 15, 2011

I have two tables, dt & dtResults.dt contains 3 columns named: vchInstrumentAnalyteID, bintAnalyteCodeID, & vchAnalyteCode dtResults contains several columns including the columns in dt

I want to get vchInstrumentAnalyteID from the first row in dt and test if it exists in the vchInstrumentAnalyteID column in dtResults. If it exists, I want to use that value from dt to filter rows in dtResults and fill all the filtered rows with data from that row in dt. Then loop to the next row in dt.

I have this code, which is close to what I need, but I can't get it working.

' put analyte data in results table
For Each drA As DataRow In dt.Rows
If

[Code]....

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Assign A Populated Datatable's Columns To Another Empty Datatable?

May 28, 2007

Is there a simple way to assign a populated datatable's columns to another empty datatable? That is, I want to copy a datatable's structure only but not its data.

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.net - ImportRow From DataTable To Another And Still Destination DataTable Is Empty?

Apr 7, 2012

I'm trying to copy one row from DataTable to another, I looked almost everywhere and I can't find a reason why this is happening, I'm using ImportRow and still the New DataTable is empty. Here's one of the answers similar I found and It's still not working!:

Dim newTable As New DataTable
Dim dsFrom As New DataTable
For Each DBShoes In list
Dim iShoeID As Integer

[code]....

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.net - Column Is Empty Then Error As Conversion From String "" To Type 'Double' Is Not Valid?

Oct 22, 2011

Using VB.Net If the grid cell value is empty, i am getting error as "Conversion from string "" to type 'Double' is not valid"Code (gridview_CellLeave)

Dim z1, z2, z3, z4 As Int32
If grvList.CurrentRow.Cells(1).Value <> "" Then
z1 = grvList.CurrentRow.Cells(1).Value
End If
If grvList.CurrentRow.Cells(2).Value <> "" Then

[Code]...

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Have A Datatable Which Has 5 Column : Copy Only Its 2 Column In And Save It Into New Datatable?

Mar 15, 2009

I have a datatable which has 5 column. It is possible to copy only its 2 column in and save it into new datatable.I used this code but it copies all the 5 column

Code:
Dim qry As DataTable = (From obj In temptable Where obj.Item("Column1") = 0 _
Select obj).CopyToDataTable
i used this one but it is not supported

Code:
Dim qry As DataTable = (From obj In temptable Where obj.Item("Column1") = 0 _
Select obj.item("Column1"), obj.item("Column2")).CopyToDataTable

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Linq To Sql Null - Check Whether A Column Is Null

Jul 15, 2011

How to check whether a column is null i use the following code but I got this error "Input string was not in a correct format."

[Code]....

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SQL Exception (adding A Null Value To A Non-null Column)

Aug 12, 2009

When I put a break point to the last if clause in the sub ("If (backOrder < 0) Then", see below) it runs until the break point, if I put the break point further below, I get the following error:

Cannot insert the value NULL into column 'OrderID', table 'WHM.dbo.OrderDetails'; column does not allow nulls. INSERT fails. The statement has been terminated.

I've discovered first hand that it only happens when prodqty is bigger then qtyOnStock, thus executing the if clause.

The code:

Private Sub NCOSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NCOSubmit.Click
Dim sqlText As String = ""

[Code]....

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Arrays - If Not String.Empty Ignoring Empty String

Aug 11, 2010

I have a array of strings and I am looping through them, but the string might be empty so I am trying this:

[Code]...

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Date With Empty/null Value?

Jun 23, 2009

i have a date control on form (vb.net) and by default its value is current date. i want to make its value to null or empty so that no date is shown and user choose from the drop down date calendar.

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Error Pop Ups When There Is Empty / Null Value

May 7, 2010

I am getting the attached error when any cell in a row is empty. How to avoid this error and to accept the null values?

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Check Null And Empty Both At A Time?

Jun 17, 2009

I am getting product id value some times null and empty from databasehere how i check if valule null and empty

productid = IIf(IsDBNull(TempDT.Rows(0).Item("productid")) =
True,
"", TempDT.Rows(0).Item("productid"))

[code].....

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How To Deserialize Empty Element As Null

Mar 7, 2012

I'm deserializing some XML from an old application into an object in my current application. The old XML often has empty elements (<SomeElement />) which are currently deserialized as empty strings (""). I agree that this is the most appropriate behaviour, but it is a minor irritant; I'd rather they were deserialized as Nothing or ideally ignored - the effect would be the same. Is there a means of ignoring these elements? Or can I have them deserialized as Nothing?

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Check If XML Node Is Empty/Null/Blank?

Apr 8, 2010

The code below works fine as long as there are values within an XML node (For example the <CPU>Intel</CPU> node below) but it throws an Exception error when the node value is blank/null whatever as in the example node <Monitor> </Monitor>.t's ok if the node value is blank, I just want to check for it and not throw an exception error.This question uses the following XML snippet below: Note: The tag <Monitor></Monitor> has no value in it.

<PCSettings>
<SystemSettings>
<CPU>Intel</CPU>

[code].....

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Check To See If Applications Settings Are Null Or Empty?

Apr 7, 2012

I have some application settings that I want to put some error checking in and the below code does not work.

If My.Settings.SmtpServer = ("") Then
MsgBox("SMTP cannot be blank!", vbExclamation, "SMTP App")
End If

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Linq Expression Returning Null Rather Than Empty Set

Nov 18, 2010

I am finding this weird issue. When I do this > activities.Where(Function(a) (Not a.IsDeleted And a.ParentId = 100) It returns an in-memory query & when I try opening it up, it throws a object not set exception. This only happens when there were no items which satisfied the condition. Shouldn't it be returning an empty set? When there are items satisfying the condition, then it returns a list & works all good.

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Made Empty Or Null Field In Datagridview

Nov 15, 2009

I key-in data from textbox to datagridvie..........the date data the format datatable is:

[Code]...

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Nested If Loops Checking For Null And Empty

May 27, 2010

I constantly find myself having to do code similar to the following.[code]Is there anyway to check for both on a single line? When i'm checking a condition for a great number of answers, I sometimes end up with conditionals 6-sets deep. If i check for null first, an error still pops up, even though VB shouldn't check since the first condition failed. i.e.[code]

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Sql - Write Database As Null Instead Of Empty Strings?

Jan 12, 2010

How can I change the following code to write to the database null instead of empty strings?

Public Sub SetChangeRequest(ByVal referenceLeaseID As Integer, _
ByVal referenceCustomerID As Integer, _
Optional ByVal custUnitNum As Object = Nothing, _

[CODE]...

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