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 ?
I'm fairly new to ASP.NET & VB.I've been asked to take an existing textbox that is automatically filled with the current date and allow the user to either add a "+" or "-" and a number or a spcific number and convert that into a date.I underdstand the basic concept on how to do this, but I'm running into some problems using the proper commands in order for this to work.The Textbox is called txtDate.What I've tried to do is this:
If txtDate = '+' Or '-' Then
DateAdd("d", txtDate, today)
End If
Here is what the whole thing looks like:
Protected
Sub
DateEnter_Click(ByVal
sender As[code].....
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.
I am using visual studio 2010. I have a text box bound to a sql datetime field.I have to be able to either set or clear the text box. I can set it to any date fine, but when I try to clear it I am unable to save the record.i am using the binding navigator to save.
View 5 Repliesi have a maskedtextbox which will accept only date in the format of "DD-MM-yyyy" no i want to insert this date in my db. i have done this successfully.
Now i want to insert null value in through that maskedtextbox .
Im writing an app which connects to a SQL Server database, via datasources / datatable.When Im looking at my .xsd I can see DataTables containing DataColumns. Each DataColumn has a 'NullValue' property which defaults to '(Throw exception)'.Because I have nulls in my tables I have gone through the fields and set all System.String fields to NullValue = 'Empty', System.int32 field to NullValue = 0.
View 1 Repliesi'm not 100% sure about sql server but i think it doesn't accept null value for date type columns but in oracle, a date column can accept a null value. and since i'm using oracle, this is causing some problems because in my form, a textbox item bound to a date column will not accept a null value. reading thru some threads, it would seem that it is not possible to pass a null value to a date type in .Net.
[Code]...
I have the following
If Trim(txtConfirmationDate.Text) <> "" Then
sqlinsert2.Parameters.AddWithValue("@CONFIRMDATE", CDate(txtConfirmationDate.Text))
Else
sqlinsert2.Parameters.AddWithValue("@CONFIRMDATE", VB.vbNull)
End If
Unfortunately, it writes "01/01/1900" to the database. How do I get it to just leave the field as NULL?
How can I get this to happen? I googled around and it seems setting the CUSTOM FORMAT to " " when the field is null will work but not for a BOUND datetimepicker.
View 12 RepliesHow can i retrieve NULL Field [ Date Out ]in sql 2005 database to a Grid View in ASP.Net. I need this field to be edited by the user.
View 2 RepliesI 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?
I am building a data based application using VB 2008 an SQL Express. I need to create textboxes on my form using code, (With & End With) method. I need a simple code string that will allow the app to check if the field to wich the textbox wil be databound is Nul, If so the textbox will not be created.
View 8 RepliesI have several records in a database that have Start and End Dates
09/15/2011 - 09/30/2011
10/15/2011 - 10/22/2011
11/01/2011 - 11/15/2011
When user stores a record, I need to make sure dates don't overlap.My simple code checks date ranges within a specific record (e.g. user enters 9/16/2011 or 10/21/2011, I throw an exception.)But, on the slim chance a user gets creative (e.g. 10/14/2011 - 10/23/2011 or even 10/14/2011 to 11/16/2011), now they have circumvented my check.BTW, the user could enter 10/14/2011 to 10/23/2011 if they were editing the record that contained values 10/15/2011 - 10/22/2011.So, I'm trying to solve this riddle with a linq query. However, what I have isn't working exactly right.
UPDATE Nevermind about code not working. While trying to provide an example to expand on Miika's repsonse, I found my answer. So, giving credit to Miika for pointing me in the right direction and posting my working code below:
Here's my code:
Private Sub CheckForOverlap(myMonth As Messages.MyMonth)
Dim am As New MyMonth()
Dim amCollection As Messages.MyMonthCollection
[code]....
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?
View 3 RepliesI'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].....
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].....
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?
View 1 RepliesI'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] ......
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.
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")
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 RepliesI 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].....
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]
View 8 Replieshow to check null excel worksheet?
View 2 RepliesI 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
I have an access form that shows a data table. when the form is opened, I want to filter the data in the date column to show only the records that don't have a date entered into the field.
View 8 RepliesWhat is the method call for checking to see if data was entered into a field? I am wanting a site to display an error message if no data was entered.
View 2 RepliesI'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.
I am using ASP.NET with SQL Server 2005.
My date get saved in the database with data type = "smalldatetime".
I am displaying the date value into a text box called txtDate with a Reader......
Dim conn As Data.SqlClient.SqlConnection
Dim Comm As Data.SqlClient.SqlCommand
Dim reader As Data.SqlClient.SqlDataReader
[Code]....
But currently my date get displayed as "2008/06/30 12:00:00 AM" and i want to display it as "30 June 2008".
I have a date I'm reading from an API in the following format:2010-03-15T00:00:00-04:00
When assigned to a date datatype in C#/VB.net, it's displayed as:
3/14/2010 11:00:00 PM //Note 3/15 is being displayed as 3/14
why is this displayed as the previous day? Is there a name for the format above?