Code, Object reference not set to an instance of an object

Question

Below code is throwing the error : Object reference not set to an instance of an object

Well i am unable to figure out what could be throwing this error. Kindly help.

Protected Sub btnSend_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSend.Click

    Try
        Dim conn As New SqlConnection
        conn.ConnectionString = ConfigurationManager.ConnectionStrings("connStr").ConnectionString

        Dim cmd As New SqlCommand
        cmd.Connection = conn
        conn.Open()


        'INSERT INTO patientDetails & implantDetails
        cmd.CommandText = "INSERT INTO patientDetails (ptFirstName,ptLastName,ptAddress,ptDistrict,ptState,ptPinCode,ptPhoneNumber,ptDOB,ptGender,ptNote,ptDateOfReg,ptPhysician,ptHospital) VALUES (@ptFirstName,@ptLastName,@ptAddress,@ptDistrict,@ptState,@ptPinCode,@ptPhoneNumber,@ptDOB,@ptGender,@ptNote,@ptDateOfReg,@ptPhysician,@ptHospital)"
        'TO PREVENT OVER WRITING OF INSERT STATEMENT
        'SIX ROWS GET INSTERTED INTO (implantDetails) FROM SINGLE INSERT STATEMENT 
        cmd.CommandText = cmd.CommandText + " INSERT INTO implantDetails (ptID,productNameID,impSerial,impDate) VALUES (@ptID,@productNameID,@impSerial,@impDate) , (@ptID1,@productNameID1,@impSerial1,@impDate1), (@ptID2,@productNameID2,@impSerial2,@impDate2), (@ptID3,@productNameID3,@impSerial3,@impDate3)"


        '=============================================================================================================
        'GET THE VALUE OF PRIMARY KEY (IDENTITY) OF patientDetails
        'GETS THE PRIMARY KEY OF LAST INSERTED ROW INTO THE TABLE
        Dim strSQL As String
        Dim priKey As Integer
        strSQL = "SELECT IDENT_CURRENT('patientDetails')"
        'Create new connection
        Dim conn1 As New SqlConnection(ConfigurationManager.ConnectionStrings("connStr").ConnectionString)

        Dim cmd1 As New SqlCommand(strSQL, conn1)
        cmd1.Connection.Open()
        'Save primary key into 'priKey'
        priKey = cmd1.ExecuteScalar().ToString()
        'PRIMARY KEY OF LAST INSERTED ROW IS INCREMENTED BY 1 (to get current the value of primary key generated)
        priKey = priKey + 1
        cmd1.Connection.Close()
        '=============================================================================================================

        cmd.Parameters.Add("@ptFirstName", SqlDbType.VarChar).Value = txtFirstName.Text
        cmd.Parameters.Add("@ptLastName", SqlDbType.VarChar).Value = txtLastName.Text
        cmd.Parameters.Add("@ptAddress", SqlDbType.VarChar).Value = txtPatientAddress.Text
        cmd.Parameters.Add("@ptDistrict", SqlDbType.VarChar).Value = DD_District.SelectedItem.Text
        cmd.Parameters.Add("@ptState", SqlDbType.VarChar).Value = txtState.Text
        cmd.Parameters.Add("@ptPinCode", SqlDbType.VarChar).Value = txtPatientPinCode.Text
        cmd.Parameters.Add("@ptPhoneNumber", SqlDbType.VarChar).Value = txtPatientPhone.Text
        cmd.Parameters.Add("@ptDOB", SqlDbType.VarChar).Value = txtPatientDOB.Text.ToString
        cmd.Parameters.Add("@ptGender", SqlDbType.VarChar).Value = DDPatientGender.SelectedItem.Text
        cmd.Parameters.Add("@ptNote", SqlDbType.VarChar).Value = txtOtherInfo.Text
        cmd.Parameters.Add("@ptDateOfReg", SqlDbType.Date).Value = DateTime.Now.ToString
        cmd.Parameters.Add("@ptPhysician", SqlDbType.VarChar).Value = RadDD_Physican1.SelectedItem.Text + " , " + txt_Physician2.Text
        cmd.Parameters.Add("@ptHospital", SqlDbType.VarChar).Value = RadDD_HospitalName.SelectedItem.Text



        '================= TABLE implantDetails  =====================================================

        'FOREIGN KEY FOR 'implantDetails' -- PatientID
        ' priKey --> primary key generated for patientDetails



        cmd.Parameters.Add("@ptID", SqlDbType.Int).Value = priKey

        cmd.Parameters.Add("@impDate", SqlDbType.Date).Value = RadDatePicker1.SelectedDate.Value
        cmd.Parameters.Add("@productNameID", SqlDbType.NVarChar).Value = RadDD_PacemakerModel.SelectedValue
        cmd.Parameters.Add("@impSerial", SqlDbType.VarChar).Value = txtPaceSerial.Text

        cmd.Parameters.Add("@ptID1", SqlDbType.Int).Value = priKey
        cmd.Parameters.Add("@impDate1", SqlDbType.Date).Value = RadDatePicker1.SelectedDate.Value
        cmd.Parameters.Add("@productNameID1", SqlDbType.NVarChar).Value = RadDD_Lead1.SelectedValue
        cmd.Parameters.Add("@impSerial1", SqlDbType.VarChar).Value = txtLead1Serial.Text

        cmd.Parameters.Add("@ptID2", SqlDbType.Int).Value = priKey
        cmd.Parameters.Add("@impDate2", SqlDbType.Date).Value = RadDatePicker1.SelectedDate.Value
        cmd.Parameters.Add("@productNameID2", SqlDbType.NVarChar).Value = RadDD_Lead2.SelectedValue
        cmd.Parameters.Add("@impSerial2", SqlDbType.VarChar).Value = txtLead2Serial.Text


        cmd.Parameters.Add("@ptID3", SqlDbType.Int).Value = priKey
        cmd.Parameters.Add("@impDate3", SqlDbType.Date).Value = RadDatePicker1.SelectedDate.Value
        cmd.Parameters.Add("@productNameID3", SqlDbType.NVarChar).Value = RadDD_Lead3.SelectedValue
        cmd.Parameters.Add("@impSerial3", SqlDbType.VarChar).Value = txtLead3Serial.Text

        cmd.ExecuteNonQuery()
        conn.Close()





        'Confirmation Message
        lblStatus.ForeColor = Drawing.Color.Green
        lblStatus.Font.Bold = True
        lblStatus.Text = "Implant Details Updated Successfully "

    Catch ex As Exception

        lblStatus.ForeColor = Drawing.Color.Red
        lblStatus.Font.Bold = True
        lblStatus.Text = ex.Message

    End Try

End Sub

Answer 1

I can't say why you get "Object reference not set to an instance of an object". You will need to debug it to see on which line it occurs.

However, I happened to notice this line:

"SELECT IDENT_CURRENT('patientDetails')"

I don't think this is very good, as this could lead to problems if two users are running the this code simultaneously. Both users will get the same value in the prikey variable, but only one of them (at most) will insert a row with that value. You need to capture the value after the fact with scope_identity.