Error on Search Button - vb.net

Question

I searched on some codes on how to do a Search Button in VB.net. But somehow, it won't work because of an error. And simply because, I cannot understand its algorithm and function. Newbie here. Anyway, here is the code for the search button:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
myConnection.Open()
crd.Clear()
fn.Clear()
ln.Clear()
Dim str As String
str = "SELECT * FROM tblReg WHERE (Code = '" & src.Text & "')"
Dim cmd As OleDbCommand = New OleDbCommand(str, myConnection)
dr = cmd.ExecuteReader
While dr.Read()
crd.Text = dr("crd").ToString
fn.Text = dr("fName").ToString
ln.Text = dr("lName").ToString
End While
myConnection.Close()
End Sub
And the error was on:
dr = cmd.ExecuteReader
And VB said:
An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
Additional information: No value given for one or more required parameters.

Answer 1

One should not follow online tutorials that teach very bad code. That code is very bad because it contains SQL injection and leaves database objects opened.
You should rewrite your code as follows:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
myConnection.Open()
crd.Clear()
fn.Clear()
ln.Clear()
Using cmd = New OleDbCommand("SELECT * FROM tblReg WHERE Code = ?", myConnection)
cmd.CommandType = CommandType.Text
With cmd.Parameters.Add(Nothing, OleDbType.VarChar, 50)
.Direction = ParameterDirection.Input
.Value = src.Text
End With
Using dr = cmd.ExecuteReader()
While dr.Read()
crd.Text = dr("crd").ToString
fn.Text = dr("fName").ToString
ln.Text = dr("lName").ToString
End While
End Using
End Using
myConnection.Close()
End Sub
You have to use question marks in place of parameters because you are using OleDbCommand that does not support named parameters.
Change OleDbType.VarChar to your actual column type.

Answer 2

Is this the link where you get the code?
http://www.visual-basic-tutorials.com/ReadFromAccess.htm
Kindly do not get the code read each data on the output shows and also check this part of the code.
crd.Text = dr("crd").ToString
fn.Text = dr("fName").ToString
ln.Text = dr("lName").ToString
are you sure crd,fname,lname are the name of your fields in your table? pls check it and also what is the field type of code? is it a text or INT that is Auto Increment? or just an INT? no matter what it is change your code.
from
str = "SELECT * FROM tblReg WHERE (Code = '" & src.Text & "')"
to
str = "SELECT * FROM tblReg WHERE Code =" & src.Text
Updated
I suggest better read or follow the whole instruction based on link where you get your code. I suggest do the same as what the link said create the same and when the program runs with no error then incorporate it with your program beacuse I tried it using VB.NET and Access and it worked Im sure you dont read it. Do this and Im sure you will not just get the code you need you will also learn.