title: VB.NET UPDATE Method
body: <p>Good day everyone. I would like to ask for help regarding my code to update specific record in the database. My back-end is Microsoft Access and front-end is Visual Basic. It gives me an error "No value given for one or more required parameters". Also, I receive a problem about "object reference not set to an instance of an object." </p>
  
  <p>Here's my code. Thank you :)</p>
  
  <pre><code>    Private Sub UpdateClient()
  
      Dim sqlUpdateClient As String = "UPDATE tblClient SET clientCompany = @clientCompany, clientStreetAddress = @clientStreetAddress, clientCity = @clientCity, clientContactPerson = @clientContactPerson, clientContactNumber = @clientContactNumber, clientEmail = @clientEmail, clientMobileNumber = @clientMobileNumber WHERE clientID = " + selectedClient
      Dim recordsAffected As Integer = 0
      Dim accessCommand As New OleDbCommand(sqlUpdateClient, accessConnection)
      accessCommand.CommandText = sqlUpdateClient
  
      accessCommand.Parameters.AddWithValue("@clientCompany", txtClientCompany.Text)
      accessCommand.Parameters.AddWithValue("@clientStreetAddress", txtClientStreetAddress.Text)
      accessCommand.Parameters.AddWithValue("@clientCity", txtClientCity.Text)
      accessCommand.Parameters.AddWithValue("@clientContactPerson", txtClientContactPerson.Text)
      accessCommand.Parameters.AddWithValue("@clientContactNumber", txtClientPhoneNumber.Text)
      accessCommand.Parameters.AddWithValue("@clientEmail", txtClientEmailAddress.Text)
      accessCommand.Parameters.AddWithValue("@clientMobileNumber", txtClientMobileNumber.Text)
  
      Try
  
          accessConnection.Open()
          recordsAffected = accessCommand.ExecuteNonQuery
  
      Catch ex As Exception
  
          lblError.Text = ex.ToString
  
      Finally
  
          accessConnection.Close()
  
      End Try
  
      If recordsAffected = 0 Then
          MsgBox("Record updated failed!", MsgBoxStyle.Exclamation, "Project Analysis System")
      Else
          MsgBox("Record updated successfully!", MsgBoxStyle.Information, "Project Analysis System")
          PopulateClientList()
      End If
  
  End Sub
  </code></pre>