Conversion from type dbnull to type integer is not valid

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SQL-Server-2008

i got this error and i don't know how to solve this.....did research but failed to get an appropriate answer.....this is my first post...sorry for my bad language

Private Sub btnNew_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNew.Click

cnnOLEDB = New SqlConnection("Data Source=SHRAYAS-PC; Initial Catalog=Bag_Shop; Integrated Security=True")

cnnOLEDB.Open()

Call clear()

Dim cmd As New SqlCommand("Select Max(emp_id) from employee_details", cnnOLEDB)
Dim maxrows As Integer = cmd.ExecuteScalar()
maxrows = maxrows + 1
txt_id.Text = maxrows
'MsgBox(maxrows)
cmd = Nothing

flag = 2
btnSave.Text = "Save"

btnNew.Enabled = False
btnDelete.Enabled = False
btnSearch.Enabled = False
btnFirst.Enabled = False
btnPrevious.Enabled = False
btnNext.Enabled = False
btnLast.Enabled = False

End Sub

What I have tried:

this the exception error details which i am getting :-

System.InvalidCastException was unhandled
Message=Conversion from type 'DBNull' to type 'Integer' is not valid.
Source=Microsoft.VisualBasic
StackTrace:
at Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(Object Value)
at Bag_Shop.employee_details.btnNew_Click(Object sender, EventArgs e) in C:\Users\SHRAYAS\Desktop\Bag Shop\Bag_Shop\employee_details.vb:line 74
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
at Bag_Shop.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:

Posted 12-Apr-16 22:51pm

Member 12456202

Updated 22-Nov-19 17:43pm

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3 solutions

Solution 2

The problem is that the when there are no records in your table the result of the

VB.NET

cmd.ExecuteScalar()

is DbNull. Which is a class. And you are trying to push it to an integer.

So my suggestion would be to first take the result of this into an implicitly typed variable(like var in C#, not sure about VB) and then check if its DbNull, push 0 to the Integer value else the actual value.

Alternate solution: Use the solution which Ashish suggested and put an ISNULL in your query itself.

Posted 12-Apr-16 23:37pm

Rahul Rajat Singh

Comments

Member 12456202 13-Apr-16 6:27am

rahul can u be little accurate...i didnt undertand you...plus i am doing my project in VB.net and i can show u screenshot of the error but i cant find any screenshot panel here 0_o?

Solution 3

1014:SUB-AUA code is invalid" to type 'Integer' is not valid.Aadhaar Service

Posted 22-Nov-19 17:43pm

Member 14665388

Comments

Richard Deeming 27-Nov-19 15:03pm

Your error message is not a "solution" to someone else's error!

If you want to ask a question, then ASK A QUESTION[^]. But you'll need to provide a lot more information that an error message if you want anyone to be able to help you.

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Nigam,Ashish · Accepted Answer · 2016-04-12T23:11:00

Solution 1

This message you are getting due to there is no records in your table("employee_details")

so you can do one thing use Isnull function in your query like this

Select ISNULL(Max(emp_id),0) from employee_details

It will return 0 for first record.

Ashish

Posted 12-Apr-16 23:11pm

Nigam,Ashish

Comments

Nigam,Ashish 13-Apr-16 6:32am

can you send me screen shots or code of after change and error details.

Member 12456202 24-Apr-16 13:54pm

ohh..ashish my error is solved brother...thank you....actually i first inserted the code at wrong place....it was my mistake...
now i have change correctly and it works erfectly...thank you once again..
:)