MySql exception was unhandled - Fatal error encountered during command execution

问题

the problem falls under this button and i get the error here:

objcommand.ExecuteNonQuery()

Once i press this button, it should update all the records in my mysql database. Here is my code (the exact code works fine for another table):

Private Sub btnModify1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnModify1.Click
    Using objconnection = New MySqlConnection("Server=localhost;database=ba-solutions;user id=root;password=")
        objconnection.Open()
        If Len(cbxCompanyName.Text) < 1 Then
            MsgBox("Please select a company name")
            Return
        End If

        If Len(txtPosition.Text) < 1 Then
            MsgBox("Please enter the postion of the shareholder in the company")
            Return
        End If

        If Len(txtNI.Text) <> 8 Then
            MsgBox("The National Insurance Number must be 8 characters")
            Return
        End If

        If Len(txtAddressLine.Text) < 1 Then
            MsgBox("Enter a First Line of Address")
            Return
        End If

        If Len(txtCity.Text) < 1 Then
            MsgBox("Enter a City Name")
            Return
        End If

        If Len(txtPostcode.Text) < 1 Then
            MsgBox("Enter a Postcode")
            Return
        End If

        If Len(txtEmail.Text) < 1 Then
            MsgBox("Enter an Email Address")
            Return
        End If

        If Len(txtPhoneNumber.Text) <> 11 Then
            MsgBox("The Phone Number must be 11 numbers ")
            Return
        End If
        'all validations for relevant textboxes
        Dim companyname As String
        Dim position As String
        Dim ninumber As String
        Dim dob As String
        Dim forename As String
        Dim surname As String
        Dim addressline1 As String
        Dim city As String
        Dim postcode As String
        Dim phonenumber As String
        Dim email As String
        postcode = txtPostcode.Text
        companyname = cbxCompanyName.Text
        position = txtPosition.Text
        ninumber = txtNI.Text
        dob = DTP1.Value
        forename = txtForename.Text
        surname = txtSurname.Text
        addressline1 = txtAddressLine.Text
        city = txtCity.Text
        phonenumber = txtPhoneNumber.Text
        email = txtEmail.Text
        sqlstring = "UPDATE shareholder_details SET position=@position, ni=@ninumber, dob=@dob, forename=@forename, surname=@surname, addressline1=@addressline, city=@city, postcode=@postcode, phonenumber=@phone, email=@email where companyname=  @company "
        objcommand = New MySqlCommand(sqlstring, objconnection)
        objcommand.Parameters.AddWithValue("@company", companyname)
        objcommand.Parameters.AddWithValue("@postion", position)
        objcommand.Parameters.AddWithValue("@ni", ninumber)
        objcommand.Parameters.AddWithValue("@dob", dob)
        objcommand.Parameters.AddWithValue("@forename", forename)
        objcommand.Parameters.AddWithValue("@surname", surname)
        objcommand.Parameters.AddWithValue("@addressline", addressline1)
        objcommand.Parameters.AddWithValue("@city", city)
        objcommand.Parameters.AddWithValue("@postcode", postcode)
        objcommand.Parameters.AddWithValue("@phone", phonenumber)
        objcommand.Parameters.AddWithValue("@email", email)
        objcommand.ExecuteNonQuery()

        btnRefresh.PerformClick()

        Dim check As Integer = objcommand.ExecuteReader.RecordsAffected
        If check < 1 Then
            MessageBox.Show("Record was not updated, please try again", "Update unsucessfull",
    MessageBoxButtons.OK, MessageBoxIcon.Error)
        Else
            MessageBox.Show("Record updated sucessfully", "Update sucessfull",
    MessageBoxButtons.OK, MessageBoxIcon.Information)
            objconnection.Close()
        End If
    End Using
End Sub

回答1:

you write

objcommand.Parameters.AddWithValue("@postion", position)

but this probably should be

objcommand.Parameters.AddWithValue("@position", position)

Other issues could be,
that you have ni=@ninumber, in your SQL statement,
but you use objcommand.Parameters.AddWithValue("@ni", ninumber) in your host variables

and in your SQL statement this looks different companyname= @company compared to your usage of other host variables

and could you try to use the same order of objcommand.Parameters.AddWithValue("@host_variable", variable) as you use in your SQL statement

回答2:

Solution that i used and it really works. This error is mostly caused by a MISSING or Incorrectly Spelled Parameter declaration. eg. @FirstName mistakenly spelled for @FirtName.

Make sure that all the parameters that are declared in the sql query are all declared in the AddwithValue Parameter declaration. (It helps to count the query versus the Addwithvalues).

The best solution is for visual studio to provide information about the missing Parameter. Use a Try-Catch block. In the catch block use Messagebox.show(ex.Innerexception.Message) instead of Messagebox.show(ex.message). This will show the exact Parameter that is missing. eg. below

Try
conCommand.Parameters.Addwithvalue("@FirstName", txtFirstName.text) conCommand.Parameters.Addwithvalue("@MiddleName", txtMiddleName.text) conCommand.Parameters.Addwithvalue("@LastName", txtLastName.text) conCommand.Parameters.Addwithvalue("@PhoneNo", txtPhoneno.text)

catch ex as exception
Messagebox.show(ex.innerexception.Message)
End Try

Hope this helps. Its really great that we share our ideas in the world of programming. Thanks for reading.

if you need more assistance. Please contact me on flashrescueagency@gmail.com. I am not a pro but i have a lot of experience in Visual Studion (VB.NET), SQL Client and MySQL Client Programming.

来源：https://stackoverflow.com/questions/22501881/mysql-exception-was-unhandled-fatal-error-encountered-during-command-execution