VB2005 MySQL Read() - NullReferenceException Error
Jan 28, 2009
I have a somewhat weird problem with a program i'am writing in VB2005. When I debug the program and start 1 backgroundworker (got 8 different backgroundworkers in the program) in VB2005 nothing goes wrong, but when i'm starting 2 or more backgroundworkers I get an NullReferenceException when trying to read from a MySQL database (withing a few minutes in debugging). This error isn't always in the same backgroundworker, but is always in the same block of code in a backgroundworker (1 of 8). I tried different approaches in getting the results I need, for example with read1.HasRows(), but this also didn't workt... the MySQL table doesn't also seem to be the problem.
Line 8 is where I get the error (read1.Read())... This is a snippet from backgroundworker1, but is also randomly happens in the other 8 backgroundworkers as well... When I'am trying to read te content of read1 is says "Nothing" when the error occures...
[Code]...
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Mar 16, 2009
I've seen so many posts on this but I just don't understand how to fix it.
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Me.txtDeletedItem.Text = objDeleteLog.Name
[b]Me.txtDeleteReason.Text = objDeleteLog.Code.Description[/b]
[code]....
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Feb 15, 2010
I have a project where the user wants an image stored in a Blob field of a MYSql database. I have been searching for info on the net but so far have not found a good solution for this.In this case the record will already exist in the database and I will need to insert the image into the existing record based on the recordid.Is there a simple way to do this perhaps with a stored procedure and an execute statement. I have very little experience with MySql and little with storing images in a database as well. Most often I will store the images as files and use a pointer in the db record but this user wants it in the db so here we are.
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Jun 4, 2010
I'm connecting to my mysql server using ODBC in vb.net, the database is shared throughout the company because it is used in an accounting program (simply accounting), each user has their own account user/pass to login to the database. I have developped a program that uses the accounting database and combines it with other information, my problem is that at least once a day I get this error when I run my program: "(10061) ERROR [HY000] [MySQL][ODBC 3.51 Driver]Can't connect to MySQL server on"and the error persists for at least 4 hours, for some reason it starts to work again later on in the day.
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Nov 21, 2009
Okay after searching two listbox's on a form I am trying to put a number as a string in a label setup for that but keep exgetting a NullReferenceexception error on the label. Label being "shippingDataLabel.text".e is my code;
Public Class MainForm
Dim fifteenShipping As Integer = 15
Dim twentyShipping As Integer = 20
[code].....
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Jun 3, 2009
I have made a tic tac toe board and when i go to debug the application i get a "NullReferenceException was unhandled".
this happens diring this part of the code:
Dim x As Integer = Val(index.Chars(0))
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Jun 3, 2009
I am getting a NullReferenceException was unhandled error when i run my debugging in this part of my code: Dim x As Integer = Val(index.Chars(0))
what can i do so this will stop and my program will work?
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Apr 11, 2011
I'm building a voting system for calls, and have tried to build it in VB. So far this is what I have:
Dim con As New OleDb.OleDbConnection
Dim dbProvider As String
Dim dbSource As String
[code]....
This code is contained within a "Record Call" button. On the form, there are four radio buttons, all with different text values which should be entered in to the "voting" table.My problem is that when I select a radio button and click on "Record Button" it then displays this error:
NullReferenceException: Object reference not set to an instance of an object.
This error is displayed on the line
dsNewRow = ds.Tables("voting").NewRow()
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May 5, 2009
I am having an issue where I try to delete a file and get the error message that it is already in use. I can not seem to figure out what is currently using the file. Maybe someone here has an idea.
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Mar 27, 2009
When I want to export the contents of my datagridview to excel 2003 I get the following error message: COMexception was unhandled Exception from HRESULT: 0x800A03EC
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Sep 18, 2011
Doing some homework on unit testing and in all honestly i just don't get why i get this error.
i got a simple method that select all text when tab and testing if the actually textbox1 is selected. I just don't get why i'm getting a nullReferenceException at target.txtbox1_Enter(sender, e)
Private Sub txtbox1_Enter(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtbox1.enter
Dim txtBox As TextBox
[Code].....
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Jan 3, 2011
I have the follwing codewhich transfer the value from NumericUpDown64 to the array Conc(0,0) which is part of the structure USerInput:
UserInput.Conc(0, 0) = NumericUpDown64.Value
When I run the program I recieve the NullReferenceException was unhandled. Object reference not set to an instance of an object.
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Apr 8, 2009
Im getting an Error saying:"NullReferenceException was Unhandled - Object reference not set to an instance of an object."I have no idea what this means as a beginner,
Me.FilmTableTableAdapter.Fill(Me.DVDDatabaseDataSet.FilmTable)
Dim con As OleDb.OleDbConnection = New OleDb.OleDbConnection("Provider=Microsoft.jet.oledb.4.0;data source=|DataDirectory|\DVDDatabase.mdb")
Dim cmd As OleDb.OleDbCommand = New OleDb.OleDbCommand("SELECT * FROM FilmTable", con)
con.Open()
[Code]...
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May 5, 2009
We sporadically get errors when we try to update a tool tip, like this:
ToolTip.SetToolTip(myLabel, customDataStructure)
The error we get is a NullReferenceException: Object reference not set to an instance of an object
Does anyone know the cause of this? Is a simple Try/Catch that eats the NullReferenceException a feasible option? We don't want our entire application to blow up when we get this.
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Mar 25, 2011
Private Sub btnSendMsg_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSendMsg.Click
Dim con As New OleDb.OleDbConnection
[code].....
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May 11, 2009
I am slowly getting used to working with classes and for the most part am getting things to work. This problem has me stumped though. Below is an abbreviated version of the code. The form class is:
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Public Class Form1
Private Lines As New List(Of DblLine)
[code].....
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May 27, 2012
I basically made a listbox, a button, and a popup window. The button openes the popup window, in that window you type some text, press "OK" and the text gets added to a list box. Simple right? Guess not...-Textbox1 is the textbox in wich you input text.-Label1 is the label on the popup window that tells you what to do. It's text is either "Edit name:" or "Input name:"This is the function if you click "OK".
If Label1.Text = "Edit name:" And Textbox1.TextLenght > 0 Then
Form1.name_list.Items.Remove(Form1.name_list.SelectedItem)
Form1.name_list.Items.Add(ime_osebe.Text)
Else
[code].....
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Jan 21, 2011
Debugging Error "NullReferenceException Was Unhandled'. I have the following code on my form
[code]...
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May 11, 2011
Error occuring at line: SqlDataSource3.UpdateParameters("TechID").DefaultValue() = CInt(technicianRow("TechID"))
Here is full VB code:
[code]....
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Jun 20, 2012
I'm trying to add objects from a class I created using data from an excel worksheet to a list using a for loop [code]When I run it I receive "System.NullReferenceException was unhandled by user code Message=Object reference not set to an instance of an object."
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Mar 26, 2011
[code] this is my code n i want to store data at runtime in the my database.i used data base as an access07 and my platform is vb.net..Now come to the point when i run the project it terminates when i'm inserting my data in the access file.[code]
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May 22, 2012
I have been trying to figure out the source of error in my application. What this function (GetConcentrations()) is to display data from my database onto a DataGridView. The function is called in the PageLoad but works fine but when I call it in another Sub, I get this error.
Here is the code:
Private Sub GetConcentrations()
Dim conString As String = ConfigurationManager.ConnectionStrings("dbAsthmaConnectionString").ConnectionString
Me.dataAdapter = New SqlDataAdapter("Select * from tblConcentrations", conString)
[code]....
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Jan 19, 2009
My code
Dim pointer As Integer, index As Integer
For pointer = 1 To 6
For index = 0 To 5999
[CODE]...
All i get is an error message saying NullReferenceException was unhandled the bold part is were it says the error is
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Nov 20, 2010
vb2005 crystal reports : Name 'CrystalReportViewer1' is not declared error
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Aug 14, 2009
I'm trying to run a simple database and im getting a "System.NullReferenceException" error ) & "Additional Information:Object reference not set to an instance of a object" .
txtItemName.Text = rowCurrent.Item("ItemName") <-- highlighted in yellow
Code is as follows:
vb.net
Imports System.Data.OleDB
----------------------------------------------------
Public Class Form1
[code]....
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Jul 16, 2009
i have encountered this error Variable 'dsNewRow' is used before it has been assigned a value. A null reference exception could result at runtime when i click on the button to insert data into my ms access database.
[Code]...
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Aug 3, 2011
getting connected using an app.config instead of hardcoding since yesterday evening and I either can't find any more info on the net that helps or I'm too new to understand it all. The exception is occurring on the line assigning the connectionstring to 'returnvalue'.
Imports System.Configuration
Imports System.Data.SqlClient
Public Class Form1
[code]...
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Dec 7, 2011
So, concering my project: I am trying to control an RC Car via Kinect, until now I got it working with key control only (eg WASD). So, I am using a Velleman K8055 Interface Board + the Kinect and VB Windows Forms. So far, so good, I created 4 Forms: menu, info, kinect-controls + wasdcontrols window. The error only occurs for my kinect-controls window (german name: Steuerung.vb) & that's my source
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Feb 7, 2011
I have created a very basic web service in vb.net using vs 2008. When I run the service within visual studio debugger, the service runs fine and gives me the expected results. When I deploy the service to the server and invoke it from a client, it always throws a NullReferenceException error when trying to access the data. More specifically when I call the DbConnection open() method within a dbhelper executeScalar method.
I'm using a custom dbhelper class I found on the web here: [URL] The only thing I've changed is the _factory at the top points to Providers.Odbc (since I'm using a ODBC connection). Like I said previously, the service (and the dbhelper class) work as expected within VS- it's only once I deploy it that it seems to bomb out. I've even tried hard coding the connection string in case it was having problems getting that but no difference there.
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Jan 7, 2010
My pc is a Vista SP1 + VS2008 I try to import a csv file into an existing access database with the following code but I have the message that the database is only in read access and I can't update it with the csv file.I tested the code on an other pc with XP and VS2005 and it works.
[Code]...
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