Why is does this error happen? "No value given for one or more required parameters" - sql

Question

When I try to click the Button1 ,2 and 3. The error that is stated below happens. This error always occur when I have two tables on my database.
No value given for one or more required parameters
This is my code
Imports System.Data.OleDb
Module MSAccessConnection
Public Function OpenConnection() As String
Dim connString As String = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=G:\MerdoresNew\OrderData.accdb"
Return connString
End Function
End Module
Public Class Order
Public total As Integer
Public ordered As Integer
Public ordered2 As Integer
Public ordered3 As Integer
Public price As Integer
Dim myConnection As OleDbConnection = New OleDbConnection
Private Sub Order_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'OrderDatabaseDataSet.Items' table. You can move, or remove it, as needed.
End Sub
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
myConnection.ConnectionString = OpenConnection()
myConnection.Open()
'the query:
Dim cmd As OleDbCommand = New OleDbCommand("SELECT [Price] FROM [Items] where Item='Cheese Burger'", myConnection)
Dim dr As OleDbDataReader = cmd.ExecuteReader
' the following variable is hold true if user is found, and false if user is not found
Dim Found As Boolean = False
While dr.Read
Found = True
price = dr("Price")
End While
If Found = True Then
ordered = TextBox1.Text * price
Else
MsgBox("Saved!")
Me.Close()
End If
myConnection.Close()
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
myConnection.ConnectionString = OpenConnection()
myConnection.Open()
'the query:
Dim cmd As OleDbCommand = New OleDbCommand("SELECT [Price] FROM [Items] where Item='Ham Burger'", myConnection)
Dim dr As OleDbDataReader = cmd.ExecuteReader
' the following variable is hold true if user is found, and false if user is not found
Dim Found As Boolean = False
While dr.Read
Found = True
price = dr("Price")
End While
If Found = True Then
ordered2 = TextBox2.Text * price
Else
MsgBox("Saved!")
End If
myConnection.Close()
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
total = ordered + ordered2 + ordered3
Form1.TextBox1.Text = total
End Sub
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
myConnection.ConnectionString = OpenConnection()
myConnection.Open()
'the query:
Dim cmd As OleDbCommand = New OleDbCommand("SELECT [Price] FROM [Items] where Item='Chicken Sandwich'", myConnection)
Dim dr As OleDbDataReader = cmd.ExecuteReader
' the following variable is hold true if user is found, and false if user is not found
Dim Found As Boolean = False
While dr.Read
Found = True
price = dr("Price")
End While
If Found = True Then
ordered3 = TextBox3.Text * price
Else
MsgBox("Saved!")
End If
myConnection.Close()
End Sub
End Class

Answer 1

I don't see where you are passing your connection string to the button click handler. You DIM the connection string as connString, but you never call it in the handler.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
myConnection.ConnectionString = OpenConnection() <----- Change ConnectionString to connString
myConnection.Open()
I think that's the variable that you're missing. I would have commented but I don't have enough rep to comment yet.