I Cannot Update my database - sql

Question

Whats wrong with these?
My module is:
Imports System.Data.OleDb
Module Module1
Public con As OleDbConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\CITeval\system7\system7\evaluation.mdb")
Public da As OleDbDataAdapter
Public dr As OleDbDataReader
Public cmd As OleDbCommand
Public ds = New DataSet
Public CurrentRow As Integer
Public sql As String
End Module
btn update
Try
Dim Str As String
Str = "update studentsrecord set IDNumber="
Str += """" & txtIDNumber.Text & """"
Str += " where IDNumber="
Str += txtIDNumber.Text.Trim()
con.Open()
cmd = New OleDbCommand(Str, con)
cmd.ExecuteNonQuery()
con.Close()
con.Open()
Str = "update studentsrecord set FirstName="
Str += """" & txtfirst.Text & """"
Str += " where IDNumber="
Str += txtIDNumber.Text.Trim()
con.Open()
cmd = New OleDbCommand(Str, con)
cmd.ExecuteNonQuery()
con.Close()
con.Open()
Str = "update studentsrecord set LastName="
Str += """" & txtlast.Text & """"
Str += " where IDNumber="
Str += txtfirst.Text.Trim()
cmd = New OleDbCommand(Str, con)
cmd.ExecuteNonQuery()
con.Close()
con.Open()
Str = "UPDATE studentsrecord set Course="
Str += """" & cbocourse.Text & """"
Str += " where IDNumber="
Str += txtIDNumber.Text.Trim()
cmd = New OleDbCommand(Str, con)
cmd.ExecuteNonQuery()
con.Close()
con.Open()
Str = "update studentsrecord set Password="
Str += """" & txtpassword.Text & """"
Str += " where IDNumber="
Str += txtIDNumber.Text.Trim()
cmd = New OleDbCommand(Str, con)
cmd.ExecuteNonQuery()
con.Close()
ds.Clear()
da = New OleDbDataAdapter("SELECT * FROM studentsrecord ORDER BY ID", con)
da.Fill(ds, "evaluation")
MsgBox("Updated Successfully...")
Catch ex As Exception
MsgBox(ex.Message & "," & ex.Source)
Finally
If con.State = ConnectionState.Open Then con.Close()
End Try

Answer 1

You don't have to issue a separate UPDATE statement for each field, you can update multiple fields in a single UPDATE statement. Also a better choice is to use parametrized query instead of concatenating strings.
Try this inside of your TRY/CATCH block:
Dim Str As String
Str = "update studentsrecord set FirstName = #FirstName, LastName = #LastName, Course = #Course, Password = #Password where IDNumber = #IDNumber "
cmd = New OleDbCommand(Str, con)
cmd.Parameters.AddWithValue("#FirstName", txtfirst.Text)
cmd.Parameters.AddWithValue("#LastName", txtlast.Text)
cmd.Parameters.AddWithValue("#Course", cbocourse.Text)
cmd.Parameters.AddWithValue("#Password", txtpassword.Text)
cmd.Parameters.AddWithValue("#IDNumber", txtIDNumber.Text.Trim())
con.Open()
cmd.ExecuteNonQuery()
ds.Clear()
da = New OleDbDataAdapter("SELECT * FROM studentsrecord ORDER BY ID", con)
da.Fill(ds, "evaluation")
MsgBox("Updated Successfully...")