System.InvalidOperationExeption {"Connection Must Be Valid And Open."}?
May 22, 2012
Here is code that I'm running. I am new to vb.net and setup a MySQL server 5.5 and I just want to insert a name into the database that is located on my computer. I can connect to it through the Server Explorer in Visual Studio 2010 premium, but when I try connecting in the program it gets to the cmd.ExecuteNonQuery() method and says that InvalidOperationException was unhandled. also I have the Connector/net version 6.45 installed
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Jan 15, 2012
I am creating a login form together with sql as may databse but when i run may program an error occur at "myData = myCommand.ExecuteReader()" stating that "Connection must be valid and open" what should i do on that to make it fix? [code]
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Jul 5, 2010
I'm trying to insert data into a mysql database, I'm using xampp as well if thats of any relevance? I keep getting this error: Connection must be valid and open.
on cmd.ExecuteNonQuery()
I'm following my Microsoft Access application that I've also written as a reference and that works perfectly.' This is the code for inserting into an access database which works and is tryed and tested:
Imports System.Data.OleDb
Public Class frmEnterDetails
'text box variables
[code]....
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Mar 15, 2012
I am building a program for a small office and I have a little problem with the code so I thought it's better to post a topic before continiue.. I have search into google and a lot of forums about database connectivity and my problem is simillar to other but a lot of things differs.The error that I get is on executeNoQuery() and it's called {"Connection must be valid and open."} Well a lot of things may related to about that.At least now from my re-search I covered all the filds of the problem and still not fixed. So please check my code for (Add new customer) button and let me know where I have mess up.
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Mar 29, 2011
[Code]...
Im clearly opening it there and its valid as i use the same connection to login with, anyone know the problem?
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Sep 15, 2011
I'm trying to make a login from in vb2010 as a windows application but I keep getting a error message saying "Connection must be valid and open"My code for the sign in button is:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdok.Click
' Adminstration login
' Add code here for secure admin
[code]....
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Aug 3, 2011
i have an application. which is executed after every 5 mins. i have an open connection but it gives me the following error:
ExecuteScalar requires an open and available Connection. The connection's current state is closed.
my code is something like this. I have shown where all i am using ExceuteScalar()
Sub Main()
Try
connection.open()
cmd.ExecuteScalar()
[code]....
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Nov 30, 2008
i make a class and when i call on form then that error occurs "ExecuteNonQuery requires an open and available connection, the connection Current stat is close "
Class Code isImports System.Data.SqlClientImports System.DataImports System.StringPublic Class DatabaseKits Dim Cn As New SqlClient.SqlConnection Public Function BuildConnection() As Boolean Try Cn.ConnectionString = "Persist Security Info=False;Integrated Security=True;Trusted_Connection=Yes;database=BizAimsPro2008;server=Server-2k3s" BuildConnection =
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Dec 19, 2011
Try If functionmode = "ADD" Then
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Jul 5, 2011
I got this error..The connection was not closed. The connection's current state is open.
This is coding to add data in Ms access in vb...
Imports System.Data.OleDb Public Class Form1
[Code]...
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May 20, 2010
I'm developing a device app in VB.net that will access a SQL Server database. I need to establish a connection when the app is launched, and keep the connection open until the app is closed. I've done the following:In the Master Module:
Public CNN
As SqlConnection
In the Main menu form load:
CNN =
New SqlConnection(sqlConnString)
CNN.Open()
Then when I want to read from the database:
Dim sqlDR
As SqlDataReader
SQL = "SELECT Name FROM Table"
[code]....
When I run the same code without the global CNN, but rather dim the connection inside the Select function, all works well.
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Mar 11, 2010
I'm trying to insert a new records into database, one of those records is a "datetime"...when I type a wrong date, and try to insert those values into database, i get an error (about wrong typed date etc.)...ok, that's fine, things need to work that way. But here comes the problem, I correct the date, and then try to insert values again...here I get an error from the post title. And this doesn't work until I close that form and run it again...here's part of my code:
Dim cvLicence As New SQL
Try
cvLicence.upis("INSERT INTO blabla (itsnotimportant) VALUES ('something')")
MsgBox("everything's fine", MsgBoxStyle.Information)
[code]....
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Jun 12, 2011
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
exitwithout()
[code].....
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Jun 4, 2011
I have an VB.NET application. This Application is permanently resident in memory and minimized to the tray area because we use it very often. The problem comes in when we VPN into a client's site. These VPN connections trash all other network connections to and from our machines.Then every time my VB.NET application refreshes its database, errors start occurring, because the machine has lost connectivity to the SQL server, however, these are not at the connection level, but only when the reader attempts to read.
I am checking for connection.open, but because of the SQL connection pooling, I just get a previous connection that was valid before the network was cut. Is there anyway to check if an actual SQL connection is valid, prior to re-issuing a connection from the pool?[code]...
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Oct 21, 2009
In my program, I have a timer with a inteval set to 1000ms. The timer is executing a MySQL-command, and right now I'm opening and closing the connection each time.
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Feb 19, 2012
MVC3, VB.NET, using EF. I am working on coding up a simple function to handle checking for a valid MySQL connection. If the connection fails the test it will use the secondary server connection. This is required because our hosting provider does not provide failover or redundant MySQL servers. The problem is I tried to use a simple try catch method in the HomeController. This fails early because the Entity Framework is looking the connection that was set up when I set it up... Is there anyway to control that connection dynamically?
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Jan 21, 2011
I get the correct numbers out of the variable(in this case 11) but i cannot compare it bcuz i get this error. both values are int, cannot seem to find the problem.
Dim id = CInt(Request.QueryString("id"))
Dim uk = From hj In dc.Orders _
Where hj.UserID = id _
Select hj
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Jun 5, 2009
I have an error but will explain how i set up my db:Two tables, One is called Area and the other Postal_Code.
The aim is to assign a postal code to the area.Sometimes we add postal codes and sometimes these codes change or need to be deleted.I used the wizard to create the datasets and dropped them on two forms linked to a SQL db.We can Add,Edit,Update & Delete so all is working fine there is no relationship between te tables as they dont need to be linked, I only require the PCode to me added to the Area Table, not any ID or Index etc.
One of the fileds in the Grid on the Areas form is the Postal Code, its set to a combobox that when the user is adding it gives them a selection of postal codes to select from.I get the error when loading the datagrid on the Area form: System.ArgumentException: DatagridViewComboBoxCell value is not valid
This happens only when the postal codes are changed or deleted in the Postal codes table.
I know what causes the error - the dropdown on my Areas form looks for the value in the Postal Code table and does not find it beacause it has either been changed or deleted.Im doing this manually - I go into SQL and remove the postal code data from the record.Then the form loads with no errors.
Q: Is there any way when the Datagridview loads that I can tell it when the PCode does not exsist in the Postal Codes table that it should rather leave it blank and warn the user that there are errors they need to fix befor they can save.
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Feb 28, 2010
In this screen I want to let the user decide which elements are on shown on a label. When I hit the update button (BDUpdate_Click; see below), it first checks whether the Barcode sample text is empty. Afterwards I want to invole the refresh of the label preview. The strange thing is that the first time it works fine, but when I alter the sample text and hit the button again, I get the Error "System.ArgumentException was unhandled. Parameter is not valid." The error points to the DrawSting function in the LabelPreview_Paint Sub
Dim BarcodeLabelUpdate As Boolean
Private Sub BDUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BDUpdate.Click
If BDBarcodeSample.Text = "" Then
MsgBox("Please enter a sample text", MsgBoxStyle.Information Or MsgBoxStyle.OkOnly, ProgramTitle)
[code]....
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Dec 12, 2009
LoopBegin:
Do Until strXMLSingle.Contains("ENDOFXMLCHECK")
strXMLSingle = getTempFile.ReadLine
If strXMLSingle.Contains("<character") Then
[code]....
I have that so far. It was working great for the names part until I attempted to do the level part, now i get the following error:
System.ArgumentOutOfRangeException: InvalidArgument=Value of '1' is not valid for 'index'.
Also at the line where i use a goto statement to go back to the beginning of the loop, is there any way i can do that without a goto statement? Like a second loop statement or something?
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Apr 28, 2009
I want str4 to display on Label3, But i give me the error. Can anyone help me with that error and problem? Error: System.InvalidOperationException: Cross-thread operation not valid: Control 'Label3' accessed from a thread other than the thread it was created on.
Private Sub DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
Try[code].....
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Apr 26, 2011
"Object reference not set to an instance of an object." (Or whatever, Its been GoogleTranslated)
VBCode
Public Class Form1
Dim Link As String = "http://s3.amazonaws.com/MinecraftSkins/" & UsernameBox.Text & ".png"
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles FETCH_SKIN.Click
WebBrowser1.Navigate(New Uri(Link))
[code].....
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Aug 11, 2011
Currently, to avoid errors from being thrown up due to invalid email addresses, I do the following:
Dim mailAddress As MailAddress
Try
mailAddress = New MailAddress("testing@invalid@email.com")
Catch ex As Exception
'Invalid email
End Try
However, rather than depending on Try..Catch, is there a way of validating that the email address will be 100% valid for the MailAddress type?I know there a plenty of regex functions out there for validating emails, but I'm looking for the function which the MailAddress type uses to validate its addresses.
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Sep 14, 2009
I have a main VB form (frmMain). frmMain has-a subForm (frmOPC), and declares a private member of type frmOPC WithEvents.
[Code]...
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Jul 9, 2009
I was wondering if its possible for VB to display all available COM ports that are open. he reason that I ask this is because this program will be run on various computers where the COM port will not always be the same. I have a text box now that the user can choose which com number he/she wants but if the wrong one is entered, the program crashes rather than displaying an error message. It would also be nice for the system to show which available com numbers there are
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Nov 27, 2011
This is my 1st time i deploy a system in vb and i deploy it at the desktop So after i install my system, i can see my system in the system menu.But may i know that why my system cant open in the system menu, it is not type .exe while is ClickOnce Application Reference and each time i need open to my system is from my location desktop setup.exe there, is it normal ? Besides that, may i know how to make my system install in the program file directory?
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May 27, 2010
Why do i keep getting "Keyword not valid as indentifier" error in Declare statemens even after importing system.runtime.interop?
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Nov 23, 2011
I have a .mdf file that I open through an Open Dialog Box and use in a ConnectionStringBuilder (where I have the user instance set to True). Later, in one of my button clicks, I try to open the connection (connection.Open()). It then gives me an error as follows: "Generating user instances in SQL Server is disabled. Use sp_configure 'user instances enabled' to generate user instances."
Here is my code:
Option Strict On
Imports System.Data.SqlClient
Public Class frmMain
[code]....
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May 12, 2005
I am currently working on a login page using vb.net. I would like to know how to make connection to an access database and verify that the user logged in is a valid user
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Jan 14, 2011
I'm trying to connect to a database and keep the connection open for any amount of user activity/queries within the database. Currently I have a connection that opens and closes for any query (save, update, etc...) which requires the logon process to the back-end every time the user saves etc... Is there a way to simply connect and leave the connection open so there won't be a lag time when running the query due to the logon process? This is what I'm using:
Private sConStrFormat As String = "Provider=TDOLEDB;Data Source=TDDEV;Persist Security Info=True;User ID={0};Password={1};Default Database=bcpm_ddbo;Session Mode=ANSI;"
[Code].....
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