HELP!!

Please look at my code and the instructions.

I am having a hard time saving and retrieving a table from access. My listbox is named 1stoperations, button is named btnretrieve, and the button to save the table is btnSaveTbl. SO please read.

You are going to save and retrieve the operations developed from the prior assignment in Ms. Access database, create the necessary table to save and retrieved operations Details - Create a table to save the operations - Create the necessary fields for the table - Create a button to save the content of the listbox to the database - Create a button to retrieve the content of the table into the listbox

Note* the table in the database should not exceed 10 records, when you do another save the table should be cleared and replaced with the new operations when select a line from the list box, the user should be able to modify the values/operations and save it to the listbox/database.

Calculator.VB

Imports System.Data.OleDb

Public Class Calculator

'con object

Dim con As New OleDbConnection

'command object

Dim command As New OleDbCommand

'dr object

Dim dr As OleDbDataReader

'sql string

Dim sql As String

'form load event

Private Sub Calculator_Load(sender As Object, e As EventArgs) Handles MyBase.Load

'setting connection string

'change this parameters

con.ConnectionString = "Provider = Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\TimothySwaney\source epos\Assignment one\Assignment one\Calculator.accdb"

End Sub

Dim decNum1 As Decimal

Dim decNum2 As Decimal

Dim decNum3 As Decimal

Dim count As Integer = 0

Dim strOperation As String ' Indicates the last operation (+,-,* or /) that was used. Appended to file when 'Save' is clicked

Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click

Decimal.TryParse(txtNum1.Text, decNum1)

Decimal.TryParse(txtNum2.Text, decNum2)

'Declares the obj to call from the MathOp class then uses the add subprocedure

Dim objCalc As New MathOp(decNum1, decNum2)

decNum3 = objCalc.Add()

txtNum3.Text = decNum1 & " + " & decNum2 & " = " & decNum3

strOperation = "+"

End Sub

Private Sub btnSubtract_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubtract.Click

Decimal.TryParse(txtNum1.Text, decNum1)

Decimal.TryParse(txtNum2.Text, decNum2)

'Declares the obj to call from the MathOp class then uses the add subprocedure

Dim objCalc As New MathOp(decNum1, decNum2)

decNum3 = objCalc.Subtract()

txtNum3.Text = decNum1 & " - " & decNum2 & " = " & decNum3

strOperation = "-"

End Sub

Private Sub btnMultiply_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMultiply.Click

Decimal.TryParse(txtNum1.Text, decNum1)

Decimal.TryParse(txtNum2.Text, decNum2)

' 'Declares the obj to call from the MathOp class then uses the add subprocedure

Dim objCalc As New MathOp2(decNum1, decNum2)

decNum3 = objCalc.Multiply()

txtNum3.Text = decNum1 & " X " & decNum2 & " = " & decNum3

strOperation = "*"

End Sub

Private Sub btnDivide_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDivide.Click

Decimal.TryParse(txtNum1.Text, decNum1)

Decimal.TryParse(txtNum2.Text, decNum2)

' divide num 1 by num 2 and display results

Try

Dim objCalc As New MathOp2(decNum1, decNum2)

decNum3 = objCalc.Divide()

Catch ex As DivideByZeroException When decNum2 = 0

MessageBox.Show("You Can't divide by 0. Please re-enter another value.")

txtNum2.Focus()

strOperation = String.Empty

Return

End Try

txtNum3.Text = decNum1 & " / " & decNum2 & " = " & decNum3

strOperation = "/"

End Sub

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click

lstOperations.Items.Clear()

My.Computer.FileSystem.WriteAllText("operations.txt", "", False)

End Sub

Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click

'Declared an array to hold each part of the operation. Last week I only had it displaying the answer.

Dim strOutput(3) As String

strOutput(0) = CStr(decNum1)

strOutput(1) = CStr(decNum2)

strOutput(2) = CStr(decNum3)

If (count < 10) Then

Dim outFile As IO.StreamWriter

outFile = IO.File.AppendText("operations.txt")

outFile.WriteLine(strOutput(0) & strOperation & strOutput(1) & "=" & strOutput(2))

outFile.Close()

count = count + 1

End If

End Sub

Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click

Dim inFile As IO.StreamReader

Dim strOperation As String

lstOperations.Items.Clear()

If IO.File.Exists("operations.txt") Then

inFile = IO.File.OpenText("operations.txt")

Do Until inFile.Peek = -1

strOperation = inFile.ReadLine

lstOperations.Items.Add(strOperation)

Loop

inFile.Close()

Else

MessageBox.Show("Please Save to Display.")

End If

End Sub

Private Sub input_validation(ByVal sender As Object, ByVal e As KeyPressEventArgs) Handles txtNum1.KeyPress, txtNum2.KeyPress

If (e.KeyChar < "0" OrElse e.KeyChar > "9") AndAlso e.KeyChar <> "." AndAlso e.KeyChar <> ControlChars.Back Then

e.Handled = True

End If

End Sub

Private Sub lstOperations_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstOperations.SelectedIndexChanged

'Allows you to select a previous entry.

If lstOperations.SelectedIndex = -1 Then Return

Dim strline As String = lstOperations.SelectedItem

'Array stores the different section of the string to split up.

Dim strsection As String() = strline.Split(New [Char]() {"+"c, "-"c, "*"c, "/"c, "="c})

If strsection.Length >= 3 Then

txtNum1.Text = strsection(0)

txtNum2.Text = strsection(1)

txtNum3.Clear()

End If

End Sub

Private Sub btnSaveTbl_Click(sender As Object, e As EventArgs) Handles btnSaveTbl.Click

Dim conn As New OleDbConnection()

Dim ds As New DataSet

Dim dt As New OleDbCommand

Dim cmd As New OleDbCommand

conn.ConnectionString = "Provider = Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\TimothySwaney\source epos\Assignment one\Assignment one\Calculator.accdb"

conn.Open()

cmd = New OleDbCommand(" insert values(" & txtNum1.Text & "," & txtNum2.Text & ")", conn)

cmd.ExecuteNonQuery()

MessageBox.Show("DATA SAVED")

End Sub

Private Sub btnRetrieve_Click(sender As Object, e As EventArgs) Handles btnRetrieve.Click

'using try catch block to handle the exception

Try

'command object is used to send the query to select the data from department table and con object

command = New OleDbCommand("select * from calculations", con)

'open the connection

con.Open()

'execute the command with ExecuteReader() method

dr = Command.ExecuteReader()

'read records one by one

While dr.Read()

'concatinate the values of NO1 and No2

sql = dr("NO1").ToString() + " " + dr("NO2").ToString() + " " + dr("ADD").ToString()

'add the Items in the listbox

lstOperations.Items.Add(Sql)

End While

Catch ex As Exception

'showing exception in messagebox

MessageBox.Show(ex.Message)

Finally

'close the connection

con.Close()

End Try

End Sub

End Class