VB.NET:Updating record in Ms Access - vb.net

Question

I am creating an employee timing sheet in which they have to insert their timings through pressing timein and timeout buttons. For timein I am creating a new record in database, for that person, and for timeout I am using UPDATING command to update that existing record. Here is my code:
Dim cb As New OleDb.OleDbCommandBuilder(ssda)
cb.QuotePrefix = "["
cb.QuoteSuffix = "]"
con.ConnectionString = dbProvider & dbSource
con.Open()
Dim str As String
str = "UPDATE emp_timing SET emp_timing.emp_timeout = '" & OnlyTime & "' WHERE (((emp_timing.emp_code)='" & TextBox1.Text & "') AND ((emp_timing.day)=" & Now.ToString("MM/dd/yyyy") & "))"
Dim cmd As OleDbCommand = New OleDbCommand(str, con)
Try
cmd.ExecuteNonQuery()
cmd.Dispose()
con.Close()
MsgBox("Data added")
TextBox1.Clear()
TextBox2.Clear()
TextBox1.Focus()
ComboBox1.SelectedIndex = -1
Catch ex As Exception
MsgBox(ex.Message)
End Try
My code is working fine but the problem is that it is not updating records in database.
Datatype for fields in Access:
emp_code = Number, emp_timeout = Text, day = Date/Time.

Answer 1

As usual this is caused by your code not using the Parameters collection to pass values to the database engine. This is not really understood until you hit a conversion problem as always happens with dates
str = "UPDATE emp_timing SET emp_timeout = #p1 " & _
"WHERE emp_code = #p2 AND day = #p3"
Using con = new OleDbConnection( dbProvider & dbSource)
Using cmd = New OleDbCommand(str, con)
con.Open()
cmd.Parameters.Add("#p1", OleDbType.VarWChar).Value = OnlyTime
cmd.Parameters.Add("#p2", OleDbType.Integer).Value = Convert.ToInt32(TextBox1.Text)
cmd.Parameters.Add("#p3", OleDbType.Date).Value = new DateTime(Now.Year, Now.Month, Now.Day)
Try
Dim rowsAdded = cmd.ExecuteNonQuery()
if rowsAdded > 0 Then
MsgBox("Data added")
TextBox1.Clear()
TextBox2.Clear()
TextBox1.Focus()
ComboBox1.SelectedIndex = -1
End If
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Using
End Using