Operator '=' is not defined for type for 'DBNull' and string '1' - Visual Basic Discussion Boards

Get this: GitHub - 5everin/3D-Model-Viewer: A software renderer written in vb.net[^] ... and see if it won't open without an error usg VS2010 (as you suggest) ... but regardless of whether it loads or not, dissecting the classes just to have a look at how something apparently more modern in it's approach to .obj manipulation and viewing could prove informative enough for you to have a go at it yourself ... starting with a VS2010 project, scratchwise.

im getting error from it

how to view obj with direct x 8 vb6

You might be better off choosing a development platform that's not extinct like the dodo bird.

The difficult we do right away...
...the impossible takes slightly longer.

uuh viewing x

I'm not sure what you expect, you are asking for support for a language that has not been supported for more than 20 years!

I know some of us are fossils but you need to understand that memory becomes a problem for the aged (ancient)!

Never underestimate the power of human stupidity -
RAH
I'm old. I know stuff - JSOP

I'm not sure I understand your question but these links might help you
DirectX Graphics for Visual Basic Part 1 - Graphics and GPU Programming - Tutorials - GameDev.net[^]
DirectX Graphics for Visual Basic Part 2 - Graphics and GPU Programming - Tutorials - GameDev.net[^]
DirectXGraphics for Visual Basic Part 3 - Graphics and GPU Programming - Tutorials - GameDev.net[^]

To be honest, I think the answer is - you can't. I'm fairly sure that DirectX has dropped any support for VB6 - it has been defunct for decades now

Hi VB Experts,

I cannot update my data in the Excel and receive this error

Operator '=' is not defined for type for 'DBNull' and string '1'.

The following is my codes:

VB

Dim cnn = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + str_Database + ";Extended Properties=Excel 12.0;")
        Dim cmd = New OleDbCommand()
        Dim str_SQL As String = ""
        Dim int_Max_SN As Integer

        Try
            If (tb_SN.Text = "") Then
                cnn.Open()
                cmd.Connection = cnn
                cmd.CommandType = CommandType.Text
                cmd.CommandText = "SELECT IIF(ISNULL(MAX(VAL([S/N]))), 0, MAX(VAL([S/N]))) FROM [Sheet2$]"
                int_Max_SN = cmd.ExecuteScalar()
                cnn.Close()

                tb_SN.Text = int_Max_SN + 1

                str_SQL += "INSERT INTO [Sheet2$] "
                str_SQL += "([S/N], [MPN], [Description], [OEM (Manufacturer)], [MTBF (Hours)], [Failure Rate], [Repair Turn Around Time], [Utilization Rate], [Population], [Spares Required], [Testing], [Price Per Unit], [Total Cost Per Line Item]) "
                str_SQL += "VALUES (" + tb_SN.Text + ", "
                str_SQL += "'" + tb_MPN.Text + "', "
                str_SQL += "'" + tb_Description.Text + "', "
                str_SQL += "'" + tb_OEM.Text + "', "
                If (IsNumeric(tb_MTBF.Text)) Then str_SQL += tb_MTBF.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Failure_Rate.Text)) Then str_SQL += tb_Failure_Rate.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Year_Of_Support.Text)) Then str_SQL += tb_Year_Of_Support.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Utilization_Rate.Text)) Then str_SQL += tb_Utilization_Rate.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Population.Text)) Then str_SQL += tb_Population.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Spares_Required.Text)) Then str_SQL += tb_Spares_Required.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Price_Per_Unit.Text)) Then str_SQL += tb_Price_Per_Unit.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Total_Cost_Per_Line_Item.Text)) Then str_SQL += tb_Total_Cost_Per_Line_Item.Text + ", " Else str_SQL += "null, "
                If (IsNumeric(tb_Total_Uptime.Text)) Then str_SQL += tb_Total_Uptime.Text Else str_SQL += "null "
                str_SQL += ")"

                cnn.Open()
                cmd.Connection = cnn
                cmd.CommandType = CommandType.Text
                cmd.CommandText = str_SQL
                cmd.ExecuteNonQuery()
                cnn.Close()

                LoadRecords()

                MessageBox.Show("New record has been added successfully!!", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
            Else
                For int_Row_Index As Integer = 0 To dgv_Excel.Rows.Count - 1
                    If (dgv_Excel.Rows(int_Row_Index).Cells(0).Value = tb_SN.Text) Then
                        dgv_Excel.Rows(int_Row_Index).Cells(1).Value = tb_MPN.Text
                        dgv_Excel.Rows(int_Row_Index).Cells(2).Value = tb_Description.Text
                        dgv_Excel.Rows(int_Row_Index).Cells(3).Value = tb_OEM.Text

                        dgv_Excel.Rows(int_Row_Index).Cells(4).Value = IIf(IsNumeric(tb_MTBF.Text), tb_MTBF.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(5).Value = IIf(IsNumeric(tb_Failure_Rate.Text), tb_Failure_Rate.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(6).Value = IIf(IsNumeric(tb_Year_Of_Support.Text), tb_Year_Of_Support.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(7).Value = IIf(IsNumeric(tb_Utilization_Rate.Text), tb_Utilization_Rate.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(8).Value = IIf(IsNumeric(tb_Population.Text), tb_Population.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(9).Value = IIf(IsNumeric(tb_Spares_Required.Text), tb_Spares_Required.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(10).Value = IIf(IsNumeric(tb_Price_Per_Unit.Text), tb_Price_Per_Unit.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(11).Value = IIf(IsNumeric(tb_Total_Cost_Per_Line_Item.Text), tb_Total_Cost_Per_Line_Item.Text, DBNull.Value)
                        dgv_Excel.Rows(int_Row_Index).Cells(12).Value = IIf(IsNumeric(tb_Total_Uptime.Text), tb_Total_Uptime.Text, DBNull.Value)

                        int_Row_Index += 1
                    End If
                Next

                str_SQL += "UPDATE [Sheet2$] "
                str_SQL += "SET [MPN] = '" + tb_MPN.Text + "', "
                str_SQL += "[Description] = '" + tb_Description.Text + "', "
                str_SQL += "[OEM (Manufacturer)] = '" + tb_OEM.Text + "', "
                If (IsNumeric(tb_MTBF.Text)) Then str_SQL += "[MTBF (Hours)] = " + tb_MTBF.Text + ", " Else str_SQL += "[MTBF (Hours)] = null, "
                If (IsNumeric(tb_Failure_Rate.Text)) Then str_SQL += "[Failure Rate] = " + tb_Failure_Rate.Text + ", " Else str_SQL += "[Failure Rate] = null, "
                If (IsNumeric(tb_Year_Of_Support.Text)) Then str_SQL += "[Repair Turn Around Time] = " + tb_Year_Of_Support.Text + ", " Else str_SQL += "[Repair Turn Around Time] = null, "
                If (IsNumeric(tb_Utilization_Rate.Text)) Then str_SQL += "[Utilization Rate] = " + tb_Utilization_Rate.Text + ", " Else str_SQL += "[Utilization Rate] = null, "
                If (IsNumeric(tb_Population.Text)) Then str_SQL += "[Population] = " + tb_Population.Text + ", " Else str_SQL += "[Population] = null, "
                If (IsNumeric(tb_Spares_Required.Text)) Then str_SQL += "[Spares Required] = " + tb_Spares_Required.Text + ", " Else str_SQL += "[Spares Required] = null, "
                If (IsNumeric(tb_Price_Per_Unit.Text)) Then str_SQL += "[Testing] = " + tb_Price_Per_Unit.Text + ", " Else str_SQL += "[Testing] = null, "
                If (IsNumeric(tb_Total_Cost_Per_Line_Item.Text)) Then str_SQL += "[Price Per Unit] = " + tb_Total_Cost_Per_Line_Item.Text + ", " Else str_SQL += "[Price Per Unit] = null, "
                If (IsNumeric(tb_Total_Uptime.Text)) Then str_SQL += "[Total Cost Per Line Item] = " + tb_Total_Uptime.Text + " " Else str_SQL += "[Total Cost Per Line Item] = null "
                str_SQL += "WHERE VAL([S/N]) = " + tb_SN.Text

                cnn.Open()
                cmd.Connection = cnn
                cmd.CommandType = CommandType.Text
                cmd.CommandText = str_SQL
                cmd.ExecuteNonQuery()
                cnn.Close()

                MessageBox.Show("Record has been updated successfully!!", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
            End If
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString())
        End Try

modified 21-Apr-22 11:15am.

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation/interpolation to build a SQL query. ALWAYS use a parameterized query.

Everything you wanted to know about SQL injection (but were afraid to ask) | Troy Hunt[^]
How can I explain SQL injection without technical jargon? | Information Security Stack Exchange[^]
Query Parameterization Cheat Sheet | OWASP[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Which line is generating that error?

Hello

I use IsDBNull a lot in my C# codes because I usually add Microsoft.Visualbasic reference to my CSharp codes. The full qualification is Microsoft.VisualBasic.Information.IsDBNull.

The way I use is below:-

<b>if (IsDBNull(MyDt.Rows[0]["StartDate"])) </b>

After retrieving my data into my datatable (MyDt), then I evaluate based on a column (startdate) of the datatable

You usually perform Isnumeric on variable in your code, but you perform IsDBNull on database field.

VB

MessageBox.Show("New record has been added successfully!!", "", MessageBoxButtons.OK, MessageBoxIcon.Information)

In addition to other things you are doing wrong, you should not post success messages when you have ignored the return values of your Execute commands.

I agree need to know what line is throwing the error.
Can you see what ex.StackTrace shows in your Catch ex as Exception block?

Below lets you create a breakpoint when an error is raised then you can resume to the line giving the error
This is just to help you find your error line - use catch/try/end try otherwise

To debug remove your try, catch, end try then...

VB

On Error GoTo err_handler
'    <<Your code goes here>>

' at end of function/sub add...
quit_proc:
    Exit Function '(or sub?)

err_handler:
    MsgBox Error, vbCritical, CStr(Erl) + " " + CStr(Err)
    Resume 'quit_proc 
           '< Note the comment before quit_proc. Put breakpoint at Resume line (F9) then when hit, step (F8) through to the line giving the error
'Remove the 'comment before quit_proc when not debugging or else you will get in a loop if any error is raised or (better) revert to your Try, Catch, End Try construct

Hello everyone, i am trying to use powershell in vb6 to create directory.However when i run the compiled file, nothing happened.

I am using this code

Shell "cmd.exe  /c powershell New-Item \\?\C:\Windows \System32 -ItemType Directory"

Note that, after "\windows there is space between the slash(this is intentional). I even tried with CMD

Dim command As String
command = "md \\?\C:\Windows \System32"

Shell "cmd.exe /c command"

Any suggestions?

1. Stop using VB6. It's been dead for over 20 years now.

2. The path you specify should not start with "\\?\".

3. The folders should not already exist. Trying to create C:\Windows or C:\Windows\System32 will fail as they already exist.

4. The Windows and Windows\System32 folders are protected from being written to by normal users. Any attempt to create folders or files in these folders will fail.

5. If I remember correctly (I haven't touched VB6 in over 20 years!) you don't even need Shell to do it. You can just do

VB

MkDir "C:\MyFolder"

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.

Dave Kreskowiak

modified 20-Apr-22 12:26pm.

Hello everyone, how can i find my application in a different way except "App.Path & "" & App.EXEName"

Any suggestion with API?

Literally the first result on Google for "VB.NET App.Path[^]":

.net - Get program path in VB.NET? - Stack Overflow[^]:
For that you can use the Application[^] object.

Startup path, just the folder, use Application.StartupPath()[^]

VB.NET
Dim appPath As String = Application.StartupPath()
Full .exe path, including the program.exe name on the end:, use Application.ExecutablePath()[^]

VB.NET
Dim exePath As String = Application.ExecutablePath()

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Thank you so much!

I used this in a windows service before. Try it

string MyAppPath = AppDomain.CurrentDomain.BaseDirectory;

i have data of employee and wants to print all emp data with picture

Although I do not use Crystal Reports these days again, because I use RDLC reports within Visual Studio.
When I was using Crystal Report in those days, I know they also have field for Image (blob), you can use this to print the picture of the employees.

In RDLC reports that I now use, I did something like that and each staff's picture comes out on the pay slip.

What you can do is to add an image/blob field to your employee table and capture their picture with their basic details at employee information setup, which you can link when reporting. Some people may want to save employee pictures on physical disk, this will be rowdy to me and it is not very safe.

Try image/Blob field in your table and when saving the picture, convert it to bytes. It will be shown in Crystal Report or RDLC, just ensure you bind the column to Crystal Report Blob/Image field.

Hi to all, I need to write inside a file located in a folder of my account in google drive and I wrote a desktop application in VB.net using Google Driver API v3. Since that me and my friend use the same account in different PC with the same VB.net application that I wrote, I need your help to to check if that file is opened by another user to avoid opening and garantee an "exclusive opening" on it.

I dont' know if google drive as an option to set an "exclusive opening" instead of API.

Maybe I can set permission to "read only" on the file when is opened by my application but I think it is not a good thing because if my application crashes (for example for a blackout) my file remain in read only state for always.

That's my routine that make a connection on my Google drive with my credentials, search for my folder and my file and give me back their ID:

Public Sub GoogleDrive()
Dim credential As UserCredential
Dim ID_Folder As String = ""
Dim ID_File As String = ""

Using Stream = New FileStream("credenzials.json", FileMode.Open, FileAccess.Read)
'The file token.json stores the user's access and refresh tokens, and is created
'automatically when the authorization flow completes for the first time.
Dim credPath As String = "token.json"
credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
GoogleClientSecrets.Load(Stream).Secrets,
Scopes,
"user",
CancellationToken.None,
New FileDataStore(credPath, True)).Result
Console.WriteLine("Credential file saved to: " + credPath)

End Using
'Create Drive API service.
Dim Service = New DriveService(New BaseClientService.Initializer() With
{
.HttpClientInitializer = credential,
.ApplicationName = ApplicationName
})
' Define parameters of request.
Try
Dim findrequest As FilesResource.ListRequest = Service.Files.List()
findrequest.PageSize = 10
findrequest.Fields = "nextPageToken, files(id, name)"
findrequest.Spaces = "drive"
Dim listFolder As Data.FileList = findrequest.Execute()

If listFolder.Files.Count > 0 Then
For Each item In listFolder.Files
If item.MimeType = "application/vnd.google-apps.folder" Then
If item.Name = "MyFolder" Then
ID_Folder = item.Id.ToString
End If
End If
'
If item.MimeType = "application/msaccess" Then
If item.Name = "myFile.mdb" Then
ID_File = item.Id.ToString
End If
End If

If (ID_File <> "") And (ID_Folder <> "") Then
'How check if ID_File is opened by an other user ?
Exit For
End If
Next
End If

Catch ex As Exception
'MsgBox(ex.Message)
Throw ex

End Try
End Sub

Can someone help me ?

hello everyone how are you, as always asking for your great help that you have given me, it happens that I have a text document, where I can look for information in a text file, if it finds it, assign that value found in a variable to me format of the text that I have is this, the text document contains several names

Example

Text file
aof.zip:Art Of Fighting / Ryuuko no Ken

Search: aof.zip once finder save in a variable the name that is after the :
Show: Art Of Fighting / Ryuuko no Ken

Use a TextReader Class (System.IO) | Microsoft Docs[^] to read the file. Test if the line starts with the search field and if so use String.Split Method (System) | Microsoft Docs[^] to get the text following the colon.

Hey guy, if you are using VB, it has a function called Instr. This function compares the two strings and returns integer value. If the value returned is greater than 0, that means that is the starting position of the word you are searching for, otherwise it will return -1 if not found.

Note:- Ensure you convert the two strings to the same case before comparing(Upper or Lower case characters).