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
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]....
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]....
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].....
I am trying to placed several check boxes (15) in a group box or on a form. I receive the following error message in Visual Studio:
Cannot set column, "The value violates the MaxLength limit of this column".
I have some code which gets child items for a menu via the GetChildren function which takes a list of menuData: Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
If menuData.Children IsNot Nothing Then
menuData.Children.AddRange(GetChildren(menuData))
End If
Next
If I check if menudata.children isnot nothing, it always is nothing because the GetChildren function is yet to run (providing the child items, which do exist). If I remove this check and just have this code:
Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
menuData.Children.AddRange(GetChildren(menuData))
Next
Then I am presented with a Object reference not set to an instance of an object error on menuData.Children.AddRange(GetChildren(menuData))
All I want to do is check if an object is null, but no matter what I do, if it compiles, it throws a NullReferenceException just trying to check! Here's what I've done:
[Code]...
I have a dataset. I'd like to check if one item in the dataset is null or zero.
If IsDBNull(ds.Tables(0).Rows(0)("TotalCostPerUnit")) or CInt(ds.Tables(0).Rows(0)("TotalCostPerUnit") = 0 Then
Exit Sub
end if
Dim Conn As ADODB.Connection
Dim Null As String
Dim NullRecordset As ADODB.Recordset
[code]....
Im trying to check my database for a null value. If the database is null, then I want it to start the timer, otherwise I want it to skip over some stuff and automatically load the main form.
I am trying to check to see if a DataSet is null or not. If it is I would like to show a MessageBox. For some reason it is not recognizing null returns and skipping the message box and going right to the Else commands. [code]....
View 3 RepliesI have a problem with verifying db null value. Actually I don't know the syntax.
Here is the code.
If Not IsDBNull(Me.DeliveryReviewDataSet.Delivery(Me.CustomerIDListBox.SelectedIndex).Signature) Then
"Signature" is the image field (binary data).
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If MyBase.Dispose(disposing) <> DBNull.Value Then
Dispose() = DBNull.Value
[Code]....
I am getting error
1) Expression does not produce a value.
2)Expression is a value and therefore cannot be the target of an assignment.
I retrieve data from database like below. How do I check whether the value retrieved from database is null?
[Code]...
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.
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]....
I am working on a program that has many integers (q1, q2, etc.), and each of them can be 0 or 1. This is dependent on which radiobuttons are selected. I need it to check and make sure that all of the integers have a value, but since "Null" is the same as "0",
View 8 RepliesI have multiple textboxes that are saved using my settings and buttons to add them to the clipboard.
The problem is when the textbox is blank and I click on the copy button.
The saving to my.settings happens on close so when someone enters text that they plan on saving later and then clicks the copy button, whammo it crashes.
Here is the code that is failing and I need to check to make sure that there is a value before setting the text on the windows clipboard.[code]...
I just want to check and see if this object is null. if i do not and it is my applications closes.I have also looked into a null reference exception. I will do whatever as long as it handles "null".[code]
View 2 RepliesHow can I check if a datatable has never been set ? or Null or Nothing ? I don't mean empty Datatable ... For example,
[Code]...
[if me.textbox1.text= system.dbnull then msgbox("please inter a value")] it says system.dbnull can't be used as an expression so how can i check the if the textbox has a null value
View 13 RepliesTable contains 2 columns Tags10 and TU. Its values are:
NDX___________TUI48
JJI_________ NULL
CmdSelect.CommandText = "Select * From Tags Where Tags10='" & s_temp02 & "'" 'OK
ReaderSelect= CmdSelect.ExecuteReader() 'OK
[code]....
How to check this? If NULL there is nothing to do, if not NULL, we should put the value into s_temp03.
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?
View 5 RepliesUsing VS2005, VB.Net, Dot Net 2.0, SQL Server 2000. If have some Columns (varchar and numbers) in a DataRow that I want to set to DBNull in the database. The fields as defined as Nullable in SQL DB table.
I have some fields that are populated when loaded but I want to update to be null using the ADO.Net data objects. If I try and use Row("FieldName") = DBNull.Value a 0 gets written to number fields (not sure what gets written to varchar fields.) What code should be used to update fields to Null using ADO.Net dataobjects?
[Code]...
I want to display a message if the value of cell of my datagridview is Null.
View 1 RepliesWhat im trying to do is check a row for null values in my datagridview before saving the data back to my access database, in particular the first columns cell of the new row being added. This is the code I have so far'
Private Sub LatheprogramsBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LatheprogramsBindingNavigatorSaveItem.Click
Dim test As String = Me.LatheprogramsDataGridView.Columns(1).ToString()
[code]....
i hav two openfilefialogs(1 and 2). So i also have a listbox. the files opened with the openfiledialogs will be added to the listbox. and when i need to open the files i need to see if they are from which openfiledialog. so
it is like this.
Path.GetDirectoryName(OpenFileDialog1.FileName) & "" & Form3.ListBox1.SelectedItem.ToString
'if this returns a null then go to this
Path.GetDirectoryName(OpenFileDialog2.FileName) & "" & Form3.ListBox1.SelectedItem.ToString
Check multiple expressions for null?I have this bit here[code]...
View 8 Replies I am getting product id value some times null and empty from databasehere how i check if valule null and empty
productid = IIf(IsDBNull(TempDT.Rows(0).Item("productid")) =
True,
"", TempDT.Rows(0).Item("productid"))
[code].....
DataGridViewX.CurrentRow.Cells.Item(0).Value.ToString
If the item is blank and no data is entered it will throw a null exception, so the question is that how can I check if the item is null or not? Even using this:
If DataGridViewX.CurrentRow.Cells.Item(0).Value.ToString IsNot Nothing Then ...
Will throw the exception!
I have a sub that updates a form on certain occasions. Sometimes I need to update a form when some of the entries in my table will still have a NULL value. I used this code to prevent the sub from trying to fill the form fields with NULL data:
[Code]...