Checking For Null Value In Specific Column
Mar 15, 2012
I'm working with a database application and i want to check if there is a null value in a specific column but it works only when its not null but if its null it throws an exception automatically. I tried to change the null value property of this column but I'm not able it shows a message that its not a valid property. I tried to change the source code in the code editor but it changes back automatically. Is there a way that I can work around this?
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Oct 11, 2011
here's the scenario. There's 2 types of employees; Worker and Manager. The worker will have to access the page 'worker.aspx' and the Manager will have to access the page 'manager.aspx'. In my login database (Access 2007) I have the first name, last name, username, password and job title of both workers and managers. Ex:
[Code]...
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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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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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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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Feb 17, 2012
checking im my textbox contains null valuefor example i have ten textbox how do i know if a textbox has no text in it?then gotfocus to that specific textbox?
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Sep 6, 2011
I'm using Visual Basic .NET to work with a USB HID device.Most of the time, I can receive data from it perfectly... but one out of every thousand transfers or so, my code will think it has received data when it actually hasn't.The device writes to an array of bytes. I wanted to check to see if the received packet is empty, by doing something like this:
If myDevice.dataPacket(1) <> Nothing then
myDevice.rxDataReady = False
[code].....
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Nov 14, 2011
ve a simple vb code similar to the below,
Function getvalue (ByVal Val as double) As string
Dim Num as Integer
Dim Prd as double
[code].....
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Apr 11, 2012
Is there anyway to check for a null here before it reaches this part of the code? tmpLabelData(0) = m_node.Item("CONTAINER_NAME").InnerText. Some XML has it while others do not. I cant seem to find a nice way to handle a null on these?
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Nov 15, 2011
I'm querying a SQL DB and sometimes the result is Null, so I thought I would test this but my code results in an error "Data is Null. This method or property cannot be called on Null values."
Here is a snipet of my code:
For i = 5 To 6
cmd = New MySqlCommand(query2t & i, db)
rdr = cmd.ExecuteReader()
rdr.Read()
If Not IsDBNull(rdr.GetUInt32(0)) Then
[Code] ......
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Jan 7, 2011
I have some code that is meant to check the length of the values in the text boxes, and if any of the boxes has no content the length of the string is 0 (or null). Here is the code:
If (Len(Form_MainScreen.Ctl48.Value) Or Len(Form_MainScreen.Ctl49.Value) Or _
Len(Form_MainScreen.Ctl50.Value) Or Len(Form_MainScreen.Ctl51.Value) Or _
[code]....
When one string is blank, the length check becomes "null" and so does the whole statement.But if the length checks are all not null, the if statement becomes a "1" and then procedes to execute the Do X procedure again.
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Oct 25, 2011
I have an ASP.NET application that crashes when a null date value is returned.
The code line is:
excelWorksheet.Cells("A" & xlRowCounter).Value = IIf(IsDBNull(dRow("sysdate")), "", Format(dRow("sysdate"), "MM/dd/yyyy"))
Error message:
ERROR: System.ArgumentException: Argument 'Expression' is not a valid value.
How would I check for a null date, and replace it with "" in my app ?
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Oct 15, 2010
I keep getting the error "Object reference not set to an instance of an Object" on the below highlighted line of code and I understand why. It's because I'm checking for something that hasn't even been initialized yet. My question is, what's the best way to check a DataTables row count without getting that error before refilling it?
If Not ds.Tables("tblNotes").Rows(0).IsNull(0) Then
ds.Tables("tblNotes").Rows.Clear()
End If
adp.Fill(ds, "tblNotes")
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Aug 24, 2010
I am trying to write a generic function that will check each database parameter to see if it is null, and if so, return DBNull; if not, return the object.So here is my function:
Public Shared Function CheckForNull(ByVal obj As Object) As Object
If obj <> Nothing Then Return obj Else Return DBNull.Value
End Function
[code].....
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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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Jun 25, 2009
how to check null excel worksheet?
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Apr 3, 2009
I have a DataGridView1 populated by sql searches. On the rare occasion that nothing is returned, my app cannot make use of data so I'm trying to check for null values. My code below is not correct because IsDBNull is not a member of the of the DataGridView1.
If DataGridView1.SelectedRows(0).IsDBNull Then
MsgBox("Nothing to display")
Exit Sub
End If
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Sep 7, 2009
I need to check if a value from a date column is equal to null. I can't find how to do it.
Wat I got now is:
if ds.tblBooking(row).CancelledOn.compareTo(dbnull.value) = true then
But this doesn't seem to work, I think it's because I'm using a strongly typed database.
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Feb 27, 2012
I'm implementing a State Machine in WF 4.0. In some transitions, I have added a condition where I check that some variables have the expected values. The variables are enums and booleans, and everything is fine.
However, now I tried to evaluate when a property is null. I have and argument in my workflow, let's say, 'MyArgument'. In a transition, I try to put a condition like 'MyArgument.MyProperty = Nothing'. I never developed in VB.NET, I don't know if I'm missing something here...
VS2010 gives the following error: "Error 4 Compiler error(s) encountered processing expression "MyArg.MyProp = Nothing".
Operator '=' is not defined for types 'XXXX' and 'XXXX'
The type names are exactly the same, and I have debugged VS2010 to ensure that my assembly is not loaded from 2 different locations.
How can I check if the property is null or not?
BTW, I'm using VS2010 SP 1, with .NET Platform Update 1 installed, on W7 64 bits.
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Feb 7, 2012
I am trying to implement a function for my SSRS report which will return a color value depending on the values of three dates.
[Code]...
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Jul 7, 2009
I am using following code in rowdatabound fn.
Protected Sub gvwMileStone_RowDataBound(ByVal sender As System.Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs)
[code]...
ddlEProjectLevels is dropdownlist in edititemtemplate.Whwn i click edit in 1st row ddlEProjectLevels gets loaded with data from database.But in 2nd row dropdownlist does not contain values.Again in 3rd it gets loaded from db.Means in alternate rows,when i click edit dropdownlist(ddlEProjectLevels) doesnot load values.Can anybody help?
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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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Mar 23, 2011
I have a program and I get time data from a sqldb and display it in a column in a listbox. What are the proper steps for adding the time as I iterate through the data in the column? I figure I will need to do some conversions on the time to be able to add it and display it as a total.
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Jun 15, 2012
I was wondering if it was possible to check if the file "test.txt" is open? and if so then display a message that the file is in use? My biggest problem is that the file can be opened in notepad, word, excel etc. I have some basic coding, which checks if the file is open - what I am trying to do is check if the file is currently open and if its not in use then proceed with the coding, I have the following coding so far.
Dim Process() As Process = System.Diagnostics.Process.GetProcessesByName("notepad")
Dim Process2() As Process = System.Diagnostics.Process.GetProcessesByName("word")
For Each p As Process In Process
[Code].....
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Aug 26, 2009
how do i check if a mouse was clicked in a specific coordinate plane on the form"?
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Mar 30, 2012
I have a working login script. It connects to my database but i need to have it search the column status to see if the user loging in is either admin user or mod. and so far i can't get anything to work.Here is my code i have for it checking the column
Code:If sqlquery = "Select * FROM userlist WHERE status = 'admin'" Then Form2.Show() Else Form1.Show() End If
[code]....
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Apr 16, 2011
Basically what I want to do is create a program that every now and then (maybe 10 minutes) switches between either, all the windows currently open, or a selection of all the windows currently open, then checks the colour of a location on the screen. At the moment I have the program checking the colour at a specific coordinate, so that's all good. The problem I have now is how to switch between windows.
I've thought up a few ways to do this. The windows that I care about checking all have the same name, the same process class, but different process IDs. I already managed to stick all the process IDs into an array of integers hoping that I could use them but I don't have a clue how to bring a window to front using just the process ID. So the first method would work if I could figure out a way to do that.
My second idea, which is a pretty rubbish way of doing it, would be to simply simulate pressing Alt+Tab however many times to change between windows.
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Mar 11, 2012
i'm working with a database application and i want to check if there is a null value in a specific column but it works only when its not null but if its null it throws an exception automatically
i tried to change the nullvalue property of this column but i'm not able it shows a message that its not a valid property
i tried to change the source code in the code editer but it changes back automatically
View 7 Replies
Jul 30, 2009
I have a databound DataGridView and use a button to control updates.
The problem is that if a db Column does not allow a null value an error is thrown ("Column <ID> does not allow null values") and then the datagridview automatically removes the row. This error is raised as soon as the user leaves the cell and before the update command is issued.
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Jan 24, 2011
I have a date field (smalldatetime) in a table and in particular cases I need to set the date field to null. Currently, when setting the sqlparameter.value property to a date
endDateParam.Value = "5/15/2011"
the field is updated with the proper date. However, setting it to
endDateParam.Value = System.DbNull.Value
[code]....
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