Conversion Error On Empty Additional Field
Aug 19, 2009
At run time my application gives an error of "Conversion from type "DBNull" to type "String" is not valid. In my form only one field - Add_info is an optional field which might be filled or not by the user. Before, I had an error when an apostrophe was used so i updated the code as highlighted below. This in return removed the apostrophe error but generated an error whenever there is an empty additional field.
For irow = 0 To QryColSentDataGridView.Rows.Count - 1
If QryColSentDataGridView.Rows(irow).Cells(3).Value = True Then
Try
query = "UPDATE gprdsql.TblCollections SET system_time = '" & _
Labeldate.Text & "' where prac_no ='" & _
[Code] .....
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May 26, 2011
I'm using visual basic to code a program to help with weights and center of balance on aircrafts, as I'm my unit's new air load planner. The math isn't hard to do, it's just that much of it is trial and error, and redoing all the arithmetic over and over again until the aircraft's C/B is in acceptable limits can eat some time up. So, since i'm trying to learn programming I thought this might be a good way to use it for a real-world scenario.
[Code]...
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Oct 22, 2011
Using VB.Net If the grid cell value is empty, i am getting error as "Conversion from string "" to type 'Double' is not valid"Code (gridview_CellLeave)
Dim z1, z2, z3, z4 As Int32
If grvList.CurrentRow.Cells(1).Value <> "" Then
z1 = grvList.CurrentRow.Cells(1).Value
End If
If grvList.CurrentRow.Cells(2).Value <> "" Then
[Code]...
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Feb 7, 2009
I need to add (Append) additional text to the Comment field in my access database from a RichTextBox. I am having difficulty with the sql connection syntax.
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Jan 13, 2012
I inherited a program that retrieves 3 datasets from our vendors' web services, converts it to a table and then merges the 3 tables before exporting into xml from the resulting combined table. The problem I am having is that when web services returns an empty dataset the program crashes in the attempt to create a table from the empty dataset.How do I modify this code to either create an empty table or recognize the empty dataset and skip around that particular table creation, merge and removal? There is always data in at least one of the datasets.
foreach (Branch branch in branches)
{
Console.WriteLine("Opening connection...");
Vendor.ws_ordersSoapClient VendorClient = new VendorInterface.Vendor.ws_ordersSoapClient();
[code]....
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Apr 8, 2009
a user will enter a number, n, which ranges from 1 to 30. they will also enter a "P" or an "S" (sum or product). depending on which was selected, it will calculate the sum or product of the numbers from 1 to n.i'm having a conversion error on line 5 stating "Conversion from string "S" to type 'Double' is not valid." [code]
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Sep 1, 2011
I have a field that I want to check to see if it has a value or not. But my code is not working. I am using:[code]
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May 17, 2012
I've run into a couple of errors within my program which reads a text file. When a user clicks a button to read the textfile and an exception is thrown, i have it displayed as a string in a message box, but an additional message box related to runtime error 52 'bad filename or number' has shown up and continues to pop up, even after clicking ok. I am currently working on the error itself in the textfile, but until I can work around all of the variables with reading this file, I was wondering if there is anything I can do to either prevent the runtime error box from popping up or figure out why it's popping up so many times. The really weird thing is sometimes after clicking ok on the initial message box displaying the error string, it won't pop up and other times it does, repeatedly.
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Nov 15, 2009
I key-in data from textbox to datagridvie..........the date data the format datatable is:
[Code]...
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Jul 7, 2009
We are bysy with making a crystal report in vs2005 / 2008
We want to print the address of a bussiness, see picture-1.jpg
If field-2 of the second record isnt filled in we get the the result see picture-2.jpg
In the crystal report we don't want to show the empty information of field-2, see picture-3.jpg Is it possible to create this in a crystal report?
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Jun 4, 2011
I have an array set up to receive the names of forms when they open. The form name is sent as a Form not a String therefore when I run my code I cannot check for whether the field is empty in the normal way (ie. array(1) = "") as the "" are only usable with strings!
Dim Forms(24) As Form
Dim i As Integer
Dim Free As Integer = -1
[CODE]...
I only need a solution to do the same as array(1)="" but for windows forms.
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Jan 18, 2011
I have a form and stored procedure that inserts the data from the form. It works fine except that if a field isn't filled in it doesn't insert a NULL into SQL it inserts "".
I've tried a few different ways but none seem to insert NULL, the one below still inserts "", can anyone point me in the right direction?
Here is the required part of the code, if you require more just let me know.
Dim rdr As SqlDataReader
Dim cmdInsert As SqlCommand = New SqlCommand()
cmdInsert.CommandText = "spPersonalDetailsInsert"
[Code].....
So if I enter nothing into address1 field it should write NULL to screen but it always writes NOT NULL. What does an empty form field equal? in classic ASP it was always "".
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Jan 4, 2012
I have a couple of textfields in a Windows form. One of these textfields is allowed to be NULL. When I enter a value for every field, it is all inserted, no problem. When I leave the field (txtGewicht) blank, I can't seem to be able to insert NULL in Access Database.
If Double.TryParse(txtGewicht.Text, 0) Then
klant.Gewicht = Double.Parse(txtGewicht.Text)
Else
[Code]....
This is what I get:
"Cannot set column 'Gewicht' to NULL, please use DBNull instead"
So I changed 'Nothing' to DBNull.value, but it then tells me that System.DBNull cannot be converted to type Double.
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Jan 5, 2011
Here's a sub routine that fills a data set with a table which I queried using an Inner Join statement. This output table, has all the required fields and the query works fine. However I want it like so:
If a student doesn't have a StudentPrediction.PredictedGrade Field to JOIN and it IS Empty.. Then I still would like it to display the students information just leaving the StudentPrediction.Predicted field empty.
You see I am using a ListView to display the data from when I fill the ListView, but it will only display for people who have a Predicted Grade naturally. So what steps would I need to take to ensure it displays all the information in the Student's table AND for the students who do have predictions that would also be displayed. If the student has no data on PredictedGrades then that column would be blank but the rest of the information still displayed.
Private Sub FillDataset()
Dim ConString As String = ("Data Source=USERSQLEXPRESS;Initial Catalog=StudentTeacherDB;Integrated Security=True")
Dim QueryString As String = "SELECT Student.FirstName, Student.Surname, Student.Email,
[Code] .....
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May 14, 2010
I'm using the following to populate a listbox from a sql server:[code]Is Available returns true (It's a bit in sql) or false - Is it possible to replace this with something shorter, say a checkbox or tick image?Also, is it possible to only display actual data rather than the whole field including empty characters? I have a few nchar(30) fields, the above seems to include all 30 character spaces.
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Jan 27, 2012
I try to compile a project with msbuild.exe I have this error :
vbc : error BC30136: Error creating Win32 resources: Error reading icon '"Recycle Bin Empty.ico"' -- The filename, directory name, or volume label syntax is incorrect.
This icon is the Application icon which is in the same directory of the project.vbc is started with /win32icon:"Recycle Bin Empty.ico" parameter.Don't know why MSBuild can't reach the file.
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Jul 26, 2009
This is my database: Here is my
[Code]...
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Feb 7, 2012
I am pulling data from a local MSSQL database using a stored procedure, then send the data to a web service. Every part of the component works well except for a pesky problem will a DBNull being returned from the DataRow field, when I know that the field is not null and has valid data. The database and associated INSERT statements that add to this field are designed to not allow NULL entries. When I debug break the program on or right before the line that throws the error I see that the field has valid data for the current row.If I add a null check to the code (as below) the operation continues as normal:
Dim dataResultsTable = Me.myViewTableAdapter.GetData(int)
For Each myDataRow In dataResultsTable.Rows
If worker.CancellationPending Then
[code]....
Why is the read operation returning DBNull instead of the data in the database?
EDIT: Just to be clear, the operation does return the proper data, but the data is not being saved into the variable.
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Aug 8, 2011
datetime1 and datetime2now two fields are have data ( date )in table recordi want to update only datetime2 is an emptyi am using visual basic 2010 ( visual studio 2010
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May 7, 2010
I am getting the attached error when any cell in a row is empty. How to avoid this error and to accept the null values?
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Oct 7, 2010
Code:
Private Sub RandomID()
Dim conn As MySqlConnection
conn = New MySqlConnection
conn.ConnectionString = cnString
conn.Open()
[Code] ....
I am getting error here
LastID = comm.ExecuteScalar()
When db is empty, but if db has records it is working fine.
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Sep 22, 2011
I have a couple of modal popups on my page that hold checkboxes. The checkboxes are different items that can be added to a specific product. Some products, however, have all of one type of item assigned to them. I need a way to show a message in the modal when the modal is empty.
I have tried using a Label inside the modal that says "All features are currently associated with this product." But the label leaves a space in the modal when it's visibility is set to hidden and that was annoying so I ditched that idea.
What is a good way to have a hidden message that shows up when the modal is empty?
<asp:LinkButton ID="FeatureButton" runat="server">Feature</asp:LinkButton>
<asp:Panel ID="FeaturePanel" runat="server" CssClass="modalPopup"
Style="display:none">
[Code].....
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Apr 26, 2011
To make it clear this IS homework, however this is also a method of research. i only ask when i get in binds i can not find answers to in other forums . There are so many i could spend more time[code]...
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Jun 21, 2010
i have a form with 4 text boxes on them when the user selects add the information from the textboxes saves to my database im just wondering does anyone know how i would make an error message appear if one of the textboxes was blank and stop the new data being saved until all textboxes have data in them?i did write the following peice of code but it did not work Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_
[Code]...
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Feb 11, 2009
When im using a loop in my program and i'm trying to use an Error Provider to pop up whenever a textbox in my groupbox is empty for some reason I cannot get it to work, can anyone tell me what i'm doing wrong?
For Each ctrl As Control In GroupBox1.Controls
If TypeOf ctrl Is TextBox Then
If CType(ctrl, TextBox).Text = "" Then
[CODE].............
I'm not receiving any type of error, it's just that when a textbox is blank the error provider is not doing anything.
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Aug 26, 2011
what is code i should use if i want to prevent user not to leave empty word in text box after user click save button.Oh ya, i am using visual studio 2005, databse sql 2005 .Here is my code
Private Sub btnregister_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnregister.Click
If MsgBox(" Are You Confirm", MsgBoxStyle.YesNo) = vbYes Then
[code].....
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Jul 4, 2011
i have 3 listboxes and a calculate button and a lblGrandTotalCost, the program works like this when i select an item from listbox 1 and listbox 2 then click "calculate" it shows a result in listbox 3, after repeating this rocess few times if u click the lblGrandtotalCost button it calculates the grand total of all the totals that are in listbox 3, Now i want the program to show an error message if some one click the lblcalculateGrandTotal button when listbox 3 has nothing in it or empty. how do i do that?
i wrote this code but it don't seem to work
If lstGrandTotalCost.Items = "" Then
MessageBox.Show("warning! theres nothing in listbox 3", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning)
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Feb 15, 2012
I have a database with lots of fields, some of which are still empty and are to be filled in at a later stage. Is there any way of writing an IF statement (or any other method) that will allow these empty records to be 'shown' in my textboxes in Visual Studio, without receiving the error:
Conversion from type 'DBNull' to type 'String' is not valid.
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Dec 31, 2009
I'm quite new to VB. I had open a VB6 file using VB express. Then some error arise after the conversion 1st error: Value of type 'Char' cannot be converted to 'Double' (Highlighted in Red)
Option Strict Off
Option Explicit On
Friend Class MainForm
Inherits System.Windows.Forms.Form
Private Const VendorID As Short = 6017
Private Const ProductID As Short = 2000
[Code]...
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May 25, 2011
I recently upgraded a VB 6 project to .net. I'm having a problem with this block of code:
Dim CtrlName As System.Windows.Forms.MenuItem
For Each CtrlName In Form1.Controls
'Some code here
[code].....
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