How To Assign The AppDate To NUll Like DBNull

Mar 5, 2010

I am not sure why VB makes everything such a pain. I have a fields which stores the date and time in the format required to store in MySQL database

[Code]...

Now I need to assign the AppDate to NUll like DBNull, but I am not able to do it directly. If I change AppDate to Date then I am not getting the required format.

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Assign DBNull.Value To A Variable, Or Write NULL To MSSQL Database?

Dec 3, 2009

I have a little problem regarding the use of DBNull, NULL etc. in VB.net in combination with SQL Server 2k.

More specifically, I want to do something along the lines of this:If x = 0 Then

x = DBNull.Value where x is declared by Dim x as Object. I would rather use Double, but I can't assign DBNull.Value to this, and using Object works quite well, too. But every time I hit this condition, I get an exception: A first chance exception of type 'System.InvalidCastException' occurred in Microsoft.VisualBasic.dll This is not a major show-stopper, since the database value I write x to in the next step, is NULL by default - most of the time! So I need the ability to write NULL to it. If that was not the case, I would have been able to work around this by catching exceptions, I think - but sadly, this isn't really of use then.

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DB Null - Conversion From DBNull To Single Is Invalid

May 19, 2010

Pulling a record from the DB and populating a list view but keep getting conversion from DBNull to Single is invalid (words to that effect). The code is below with bold highlighting where problem is and a bit more helpful description of error. I get this error: "Conversion from type 'DBNull' to type 'Single' is not valid." [Code]

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Asp.net 1.1 - Assign Null Value To Optional Parameters In .NET 1.1?

Dec 21, 2010

I tried DbNull.Value but no luck. How do I assign a default value as null to a string parameter that is null in VB.NET? Its litte strange to see that VB does not have anything like plain null as most of the other languages do. Also what is the difference between null and DbNull and Nothing.

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Assign Null Value To Date/time Variable?

Jun 7, 2011

Attempting to convert a possible null value into date/time field. Any easy way ?

[Code]...

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Assign A Value To Nullable Integer Via A Ternary Operator / It Can't Become Null

Apr 19, 2012

If you assign a value to a nullable integer via a ternary operator, it can't become null..While this question may seem like a duplicate of many, it is actually being asked for a specific reason.Take this code, for example: Dim n As Integer? = If(True, Nothing, 1) In that code, the ternary expression should be returning Nothing, but it's setting n to 0. If this were C#, I could say default(int?) and it would work perfectly. Now it looks like I am going to have to ditch the ternary and use a regular If block, but I really want to use the ternary. If Nothing were truly VB.NET's equivalent to C#'s default, how can you explain this behavior?

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Assign Data To An Array From A Text Box - Null Reference?

Apr 24, 2011

when i try to assign data to an array from a text box, i get a null reference exception, stating "Object reference not set to an instance of an object".

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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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"Conversion From Type 'DBNull' To Type 'Boolean' Is Not Valid" After Checking That It's Not DBNull

Jan 18, 2012

In my ASP.Net Web-Application, I'm getting this error: Conversion from type 'DBNull' to type 'Boolean' is not valid.

[Code]...

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Assign The Authority And Get A New Form To The New Assign With .net?

Mar 9, 2010

Admin assigns the authority and get a new form to the new assign in with vb.net & access. I am not sure about this,I need a way to do the new form assigned? How?Actually, this project is the admin will assign the authority to a manager, and the manager will get the password to log in. Then, the manager once log in and will get a form to set the rooms who is going to use and date, etc, this is multi-manager to handle the room setting jobs.But, I think, I got stuck, I am not sure how to do the new form, HOW DO YOU ASSIGN THIS NEW FORM FOR EACH NEW MANAGER?????? THIS IS VB.NET WITH ACCESS.

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Null Reference Exception In Line Checking For Null?

Dec 15, 2011

I have a fairly simple piece of code:

Private _PurchaseDelivery as PurchaseDelivery
Protected Overrides Sub InsertItem(ByVal index As Integer, ByVal item As PurchaseDeliveryItem)

[Code]....

Which is inside a class which overrides a custom list base. The code is occassionaly throwing an unhandled exception, System.NullReferenceException, on this line when used in production:

If _PurchaseDelivery IsNot Nothing AndAlso _PurchaseDelivery.DefaultSKUBinID.HasValue Then

DeafultSKUBinID is declared as an Integer? (Nullable Int) in the PurchaseDelivery class. I cannot see what might be causing this error, why would this be returning an error?

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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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Can't Get Rid Of DBNULL

Dec 13, 2011

I am teaching myself vb.net with visual studio 2010 and i have ran into a wall. I have a datagrid on my form that shows all of my customers that are in the dataset that was created in access 07. I have a search bar and check boxes to select which column name to search in. Whenever I search it throws up a strong typing exception,

System.Data.StrongTypingException was unhandled by user code
Message=The value for column 'PickupTime' in table 'CustomerRouteTable' is DBNull.
Source=EXBSTESTDatabase

[Code]....

I think this means that there is nothing in the field, but this is a field that nothing should be in. If i comment the throw exception out it moves on to the next one that has nothing in the field. I tried just putting 0's in all of them but it still gives the same exception.

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Error 'Arguement Null Exception Was Unhandled, Column Arguement Cannot Be Null'?

Oct 20, 2011

I am trying to create a treeview in VB.net, the data has to be loaded from MSAccess 2010 database. When I try to run this program I get error : Argument Null Exception was unhandled, 'column' argument cannot be null and the program crashes. I have pasted the code as under:

Imports System.Data.OleDb
Public Class frmRating
Private Sub frmRating_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles

[code].....

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DBNULL Error In .NET?

Nov 9, 2011

I am receiving this error on this line

ctl.Value = CType(Me.Value, DateTime)

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Handling DBNull In Dot Net?

Jan 19, 2012

I have been having an error that DBNull cannot be returned as a String and after hunting around I came up with the folowing but have had no sucess. it is very inportant that this code can handle DBNull as it will encounter this often.

[Code]...

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How To Set A Double To DBNULL In .net

Mar 10, 2010

Dim k as nullable(of double)I am INSERTING a rec in database containing K (sometimes it has some value otherwise a null) It works ok.But when i UPDATE a rec and assign a field the value of k and when k is NULL
it gives me an error that you cannot assign a NULL , you should use DBNULL.But i think DBNULL.value can only be assigned to an object not to double.

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If Syntax For Dbnull And Value?

Nov 12, 2009

I need to make something like :

if isdbnull(value) or value = something then
'do something
else

[code].....

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Replace DBNull With Zero?

Sep 29, 2009

So I'm importing Excel data using ADO into a DataTable then pushing out to an Access DB. A couple of the Excel columns have several blank cells that I would like to change to a zero before pushing it out. How can I check/change the DT null values to zero? I've done some searching but was wondering if I could do it without a loop.

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'DBNull' When Searching A DataGrid?

Dec 21, 2011

I'm writing a program for my friend as a gift. He's a movie lover, and has this Excel spreadsheet with all the movies he's watched in it. I converted the spreadsheet to an Access database,then used that database in my program. I've been going by the example in my textbook (Programming with Microsoft Visual Basic by Diane Zak), and everything been working until I put in a "Find Movie Title" button. I want to be able to search the column "Movie Title" for a title input by the user (whether it's the whole title or just a few characters)Here's the code:

Private
Sub btnFindTitle_Click(ByVal
sender As
Object,[code].....

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.net - Filtering DBNull With LINQ?

Mar 8, 2010

Why does the following query raise the error below for a row with a NULL value for barrel when I explicitly filter out those rows in the Where clause?

Dim query = From row As dbDataSet.conformalRow In dbDataSet.Tables("conformal") _
Where Not IsDBNull(row.Cal) AndAlso tiCal_drop.Text = row.Cal _
AndAlso Not IsDBNull(row.Tran) AndAlso tiTrans_drop.Text = row.Tran _

[code]....

Run-time exception thrown : System.Data.StrongTypingException - The value for column 'barrel' in table 'conformal' is DBNull.

How should my query / condition be rewritten to work as I intended?

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Asp.net - Correctly Check DBNull In VB?

Jan 13, 2012

Why does the following code: A = not IsDBNull(CurRow("BuyBook")) AndAlso CType(CurRow("BuyBook"), string) = "Yes" results in the following error:

Conversion from type 'DBNull' to type 'String' is not valid.

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Catch DBNull Across Entire Row

Nov 17, 2010

I am writing a program that pulls data from a database.For each table that I pull data from, I write a series of If Than Else Statments to catch any null values and assign Nothing so as not to throw an exception.Is there a way to check against a DBNull value without writing an If THan Else Statment for each column I am pulling from the database?

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Check Column Is DBNull Or Not?

Feb 10, 2010

I have simple app code:

Dim sw As New StreamWriter(FileName, False, System.Text.Encoding.GetEncoding(Encoding))
Dim adapterPositions As New MyDatabase1DataSetTableAdapters.PositionsTableAdapter

[Code]....

How I can check column is DBNull or not?

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Conversion Of DBNULL To String?

Apr 17, 2009

Is it possible to converty a type System.DBNULL to a string type?

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Convert DBNull To Date

Jun 5, 2011

I wants to ask how to convert DBNull to Date type?

For Each row As DataRow In dt.Rows
i = 0
Dim array As Object = row.ItemArray

[Code]....

array(i + 10) is datetime type, in the program above, if the Datetime column contains items, it still can run. However, when it loops to a row where the Datetime column does not have value of datetime (or the column is null), then an error " Conversion from type 'DBNull' to type 'Date' is not valid" is occured. I tried to use the if statements as program above but it seems like cannot works.

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Dbnull In Textboxt To Datagridview?

Nov 24, 2009

this code i pick from grauva khanna... it working..but for one coulmn only.. my question is ..how to manipulate every column with dbnull.value

'If TextBox1.Text.Trim = "" And TextBox2.Text.Trim = "" And TextBox3.Text.Trim = "" And TextBox4.Text.Trim = "" Then
'DT.Rows.Add(DBNull.Value, DBNull.Value, DBNull.Value, DBNull.Value)

[Code].....

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DBNull To Type Decimal?

Jun 6, 2011

I have a piece of code im working on and is stuck on Select Sum statement which keeps returning a Conversion from type DBNull to type Decimal is invalid. Below is the code and Im working with a Access Database. Everything works good if the Batch Number exists and its when the Batch Number does not exist.

[Code]...

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DBNull Value - Cannot Save Records

Dec 14, 2009

I have a form with some textboxes in it. Not all the boxes are mandatory fields. I also have a store procedure that saves the records to the DB. when I try to save a record, I get an error PLS-00306. I am passing the required number of parameters to the sp. When I populate all the fields, the record is saved but NOT when some fields are left blank.

If txtInvoiceRef.Text = Nothing Then
strSQL.Parameters.Add(New OracleParameter("varInvoiceID", OracleDbType.Varchar2, 50, ParameterDirection.Input)).Value = System.DBNull.Value
ElseIf txtPaymentDate.Text = Nothing Then
strSQL.Parameters.Add(New OracleParameter("varPaymentDate", OracleDbType.Date,
[Code] .....

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