incrementing different student number with sql

Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Linq
Imports System.Text
Imports System.Windows.Forms
Imports System.Data.OleDb
Namespace Dynamic_generate_id
    Public Partial Class Form1
        Inherits Form
        Private ConnectionString As String = System.Configuration.ConfigurationSettings.AppSettings("dsn")
        Private com As OleDbCommand
        Private str As String
        Private count As Integer

        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub btn_save_Click(sender As Object, e As EventArgs)
            Dim con As New OleDbConnection(ConnectionString)
            con.Open()
            str = "insert into caste(cast_code,cast_desc) values('" & lbl_castecode.Text.Trim() & "','" & txt_castename.Text.Trim() & "')"
            com = New OleDbCommand(str, con)
            com.ExecuteNonQuery()
            con.Close()
            MessageBox.Show("Records successfully Inserted")
            txt_castename.Text = ""
            autogenerated()
        End Sub
        Private Sub autogenerated()
            Dim con As New OleDbConnection(ConnectionString)
            str = "select count(*) from caste"
            com = New OleDbCommand(str, con)
            con.Open()
            count = Convert.ToInt16(com.ExecuteScalar()) + 1
            lbl_castecode.Text = "ACT00" & count.ToString()
            lbl_castecode.Enabled = False
            con.Close()
        End Sub

        Private Sub Form1_Load(sender As Object, e As EventArgs)
            autogenerated()
        End Sub
    End Class
End Namespace