Select Null Records Produces Exception Error
May 29, 2012Not sure what I am doing wrong, but here is the code.
SQL Server Express 2008 R2
VB 2010
Private Sub FillDataSetAndViewGrid()
[Code].....
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Select All Records Where A Field Is Null Using LINQ?
Jan 25, 2012I've got a table that caches calculated values for certain dates. I want to use LINQ to select all rows where the calculated value fields are null.But when I use isNothing I get an error that LINQ can't translate this into T-SQL. Is there a way to select null values with link, like this...?
Dim var = From rec As Record In myDataContext.Records Where IsNothing(rec.calculatedValue) Select rec
Other posts on stackoverflow mostly discuss how to avoid or check for null values with LINQ.
Note: I can't just set cacluatedValue's default to -1 to flag records whose calculated value has not been set (and then select those records) because I run queries that sum/average the calculated values. Selecting nulls seems cleaner and less bug-prone.
C# - Joint Query In Linq To SQL To Select All Records Even There Are Some Null In The Columns Of Foreign Keys?
Feb 2, 2011I'd like to take all suggestion either in C# or VB.NET.I have a DB diagram like the image below. I also include the database script here [URL]In the Students table, CountryId and RoomId column are allowed null. Because some records do not have info about room and country yet.Also, some students do not have essays.I'm doing a joint query with all tables. I want to select all students to project the result like this:Wanted query result.
Here's my current query that gives the result like the image below:
Dim db As New DBDataContext
Dim query = From st In db.Students _
Join c In db.Countries On c.Id Equals st.Id _
Join r In db.Rooms On r.Id Equals st.RoomId _
[code].....
current query result I got only one result back because I have (2) William NoMan record in every table. But I don't get anything about others, like (3) Sync Master who has everything but RoomId.What do I need to modify the query above so it will give me all students like in the wanted query image above?
Error 'Arguement Null Exception Was Unhandled, Column Arguement Cannot Be Null'?
Oct 20, 2011I 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].....
MySQL Null Exception Error
Jun 7, 2010I am building a VB.net application using VB Express 2008 which connects to a MySQL database. Right now, I am only selecting records, but will be writing code for update / insert. I have installed the MySQL Net Connector, most recent stable build. I have set a reference to it in project references. It makes a connection and reads just fine, no issues there at all.
My problem is this: When exiting the project (via calling "End") I am receiving a null Exception error. Here is the error[code]....
Class Giving Null Exception Error
Dec 10, 2011It's saying I cant access this object in my class. Why? I'm pretty sure Ive used this method several times before. Below is some bits of code to figure this out. Object reference not set to an instance of an object."
[Code]...
Error - Null Reference Exception Was Unhandled
Dec 14, 2009Public Class Form1
Dim int As Integer = 0
Dim CustomerTable As New DataTable
Dim instance As New InvalidOperationException()
[code].....
This is the code this exception occurs when i click on the home button of my webbrowser.or i enter any site on the combobox.
Null Exception Error When Loading Datatable?
May 20, 2010I am loading data from an excel sheet using the following code.The first test I did worked fine.But when I tried another sheet it errored on a cell that was blank"Object reference not set to an instance of an object".Even though the sheet in the first test had blank cells.I need the loop to load the blank cell in the datatable
For nRow = 1 To objSheet.UsedRange.Rows.Count - 1
dr = dt.NewRow
For nCol = 0 To objSheet.UsedRange.Columns.Count - 1
[code]...
VB 2008 - Lists And Null Value Exception Error
May 10, 2009I have one list that pushes to another list. Think of a shopping cart situation. If you double-click on the white area after the list of items in the first window, I get a null exception error when I push the info to the second window. How can I avoid that error??
Existing Code is below...
Private Sub lstBooksAudio_doubleclick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstBooksAudio.DoubleClick
If lstBooksAudio.SelectedItem = "" Then
MsgBox("Please Click on an item.")
[Code] .....
VS 2008 Getting A Null Exception Error Intermittently
Dec 30, 2009I'm hoping someone can assist. I'm still learning VB so excuse my lack of knowledge. The below code is a mashup of a code snippet I found that effectively reads from an SQLite database. The initial code snippet consisted of a textbox for input, a textbox for output, and also consisted of a datagrid to store the contents and a button to activate the lookup.
[Code]...
1 Out Of 700 Custom Controls Produces A Security Exception?
Jul 27, 2009For some reason one of my controls produces the following excecption error when adding to the VS ToolBox:Request for the permission of type System.Security.Permissions.SecurityPermissions, mscorlib, Verion=2.0.0.0, Culture=neutral etcWe have identified it is this class within the Custom Control but we not sure whyit is erroring
View 2 RepliesCatch Ex As Exception Error - CDate Function Is Null
Jun 24, 2011In the following code an error arises because the date being passed to the cDate function is Null. However, the catch statement is in error and reports index out of range on the Catch Ex as Exception line. The exception helper says the word Exception is in error and advises that it is index out of range.
View 12 RepliesError In Vb Application: Argument Null Exception Was Unhandled
Nov 10, 2009I am working on a vb windows form application with several connected forms. Its used to manipulate a MySQL database. One of the sub-forms has the following code snippet:
[Code]...
Error: Null Reference Exception Was Unhandled-object
Jul 8, 2009i have the following code but when i select button1 i get the following error: Null Reference Exception was unhandled-object reference not set to an instance of an object. - any idea's how to fix it ?i have underlined the line of code that is highlighted when the error occurs
Imports System.Data
Public Class Form1
Dim Ping As Net.NetworkInformation.Ping
[code].....
Null Exception Error Using Connection String In App.config
Sep 21, 2011I've moved my Database connection string into my app.config - however its causing a null exception error when i use it
App.Config
vb
<connectionStrings>
[Code].....
WebBrowser Error Before Navigation - Null Reference Exception
Jul 4, 2010I am getting a "null reference exception" error when I run my application, this error occurs even before the webbrowser has navigated anywhere. Why would I get this error without a webbrowser document complete occurring?
vb
Dim HTML As String = WebBrowser2.Document.Body.InnerHtml.ToString
If HTML.Contains("Submit Comment") Then EnterData() Else NextURL()
End If
I don't understand why I would get this error when I haven't even navigated anywhere? Forgot to say that this code is inside WebBrowser2 document_complete.
Dynamically Creating Objects - Error: A Null Reference Exception
Apr 13, 2011I am working on creating an application (game) for a PocketPC with Visual Studio2005 in VB/.NET. I try to dynamically create a (new)button upon clicking a label and assigning certain properties to this button. For this I used below displayed code, but this button does not appear on 'Form1' - which is big enough to display it- but creates an error: A NullReferenceException. Such occurs when you try to reference an object in your code that does not exist, but I think I just did by using'..New..' Who can tell me what is wrong and how to fix this? [Code]
View 16 RepliesError - Null Reference Exception Could Occur At Run Time When The Result Is Used
Apr 28, 2011Background: I wrote code that will output all the currently logged in User's Active Directory group names. I want the group name (ex: Acomp_user_BIG) via IdentityReference.Translate instead of the current user's SID's (ex: S-1-5-32-544) returned via IdentityReference.Value.
Here is code that I used:
Public ReadOnly Property Groups As IdentityReferenceCollection
Get
Dim irc As IdentityReferenceCollection
[Code].....
Warning Error: A Null Reference Exception Could Result At Runtime
Feb 20, 2012Due to this error I am getting a default date 1/1/1900. Variable 'dr' and 'dr1' is used before it has been assigned a value. Here's the code:-
[Code]...
Sql Server 2008 - Select Records Between Two Date Gives Error Operand Type Clash?
Dec 14, 2011i need to select some records from table Tr_cashbook between two date. the date field is newdt in which i need to compare data and the records should be shown in crystal report named rptCash2. the newdt field has datetime property. here is the code on the command button
bdcon.Open()
Dim QueryString As String
QueryString = "Select * from Tr_Cashbook where (Cast(newdt as date)>= " &
[Code]...
but this is not working when i press the command button it gives error as operand type clash: date is incompatible with int.
Null Reference Exception In Line Checking For Null?
Dec 15, 2011I 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?
SQL Exception (adding A Null Value To A Non-null Column)
Aug 12, 2009When 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]....
Get The Error "Null Reference Exception Was Unhandled" Before The Loop Ends?
Aug 1, 2011I tried adding a loop inside this loop but continue to get the error "Null reference exception was unhandled" before the loop ends.
For rowIndex = 0 To dgvVisit.RowCount - 2
MessageBox.Show(dgvVisit.Rows(rowIndex).Cells("CoPayCharge").Value.ToString)
For rowIndex1 = 0 To dgvPayment.RowCount - 2
MessageBox.Show(dgvPayment.Rows(rowIndex).Cells("CoPayPaid").Value.ToString)
Next
Next
Null Reference Exception Unhandled Error When Input Is Saved Into Array After Array Has Been Erased?
Jun 23, 2011n my project i am to enter a name and a test mark into two separate text boxes and then select the button to store the information into the arrays, one array for names and another for marks, but when it is reset using the Erase <Array> fuction andi try to re enter information, no matter what information is entered i get a "Null Reference Exception Unhandled" Error.I am using Visual Basic 2008.My code is as it says from now:
Public Class frmAdverageTestMarkCalculator
Dim ClosingMsg As String
Dim Closingtitle As String
[code].....
Hiding A Form Produces "Cannot Access Disposed Object" Exception
Apr 12, 2011I am trying to write a program that takes the input of a CSV file, makes modifications, and prompts the user on how to handle certain modifications.
I have the parsing of the CSV file complete, the handling of most of the string manipulation down, and the user interface complete, except when it comes time to move onto the next record.
I had it display the form as a modal dialog, and used me.hide() once it was over to continue with the program. However, when it gets to the next ShowDialog(), it says that the object has been disposed! I've tried a modeless dialog, with a while loop that waits for a boolean to be flipped by a button on the dialog being clicked, but that, as predicted, did not turn out so well and just shot the processor load to 100%.
One thing I notice in looking around is that I have everything based on the "home" form, the initial one that comes up when the program is run. Is this incorrect coding? Does this require the prompt being on a child form?
Commit Changes To Database Produces Error
Feb 27, 2012So I'm going through a tutorial on how to get stuff in my vb form to update a Access Database. I know, I should be using sql, but Im just learning. Anyways, here is the code..
[Code]...
.net - SQLDataAdapter Filling Datatable With Primary Key Produces Error And Exits Sub?
Aug 12, 2011Ok so this is going to take some explaining. The process I am trying to do is grab data from a table function in SQL and then fill a dataset with the returned values. I then have to run this query twice more to query an alternative number table. Then add to the same table as the previous queries.This needs to be as fast as possible, so I am currently using an adapter.fill to populate the datasets and then a dataset.merge to put them all into one table.
The problem is the query can return duplicates which waste time and space, because of this I made column 3(part_ID) the primary key to stop duplicates.When this is run with the .merge it quits at the first instance of a duplication and doesn't continue with the population.
[Code]...
Executenonquery Delete Null Records?
Jul 26, 2010I have a database which contains 60K null or blank records. These records contain several fields, all blank or null. I am using the following code, which I know works if there is text in the field, but if it is null or blank, I get negative results.
Dim
rv As
Integer
[code]....
how to check for null in an executenon query command?
Why Null Reference Exception
Jun 27, 2012visual basic application prompting me a message "Object reference not set to an instance of an object". i have 2 project in one solution. One is developed in c# and other is in vb. i am calling a method of c# project in vb project. the vb code is:[code]when i debug vb project individually it works properly and when i call vb application from c# application, it prompting error. is i missed out any .net framework reference? [code]
View 1 RepliesBindingsource.filter - Show Only Those Records That Have Null Values
Nov 7, 2009I'm trying to filter all the records in my datatable that have a NULL value for one the fields in the table, I'd like the bindingsource to show only those records that have null values.
[Code]...