'System.Data.OleDb namespace deals with the database transcation
Imports System.Data.OleDb
Public Class Conn
    Dim con As New OleDbConnection
    Dim da As New OleDbDataAdapter
    Dim dt As New DataTable
    Dim str As New System.Text.StringBuilder
    Sub New()
        'Using StrigBuilder class creating the connection
        str.Append("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=")
        'AppDomain.CurrentDomain.BaseDirectory will return the path of bin folder
        str.Append(AppDomain.CurrentDomain.BaseDirectory)
        str.Append("yogita.mdb")
        str.Append(";Persist Security Info=False")
        'MsgBox(str.ToString)
        con.ConnectionString = str.ToString

        'If connection is opened or broken or there is any problem then it will first close the connection
        If con.State = ConnectionState.Open Or con.State = ConnectionState.Broken Then
            con.Close()
        End If

        'When connection is closed it will open the connection
        If con.State = ConnectionState.Closed Then
            con.Open()
        End If
    End Sub
    'Selectdata is function that will accept the table_name and return you fill data from that data in the form of DataTable
    Function SelectData(ByVal tablename As String) As DataTable
        Dim s As String
        s = "select * from " & tablename
        Dim cmd As New OleDbCommand
        cmd.Connection = con
        cmd.CommandType = CommandType.Text
        cmd.CommandText = s
        da = New OleDbDataAdapter(cmd)
        da.Fill(dt)
        cmd.Dispose()
        Return dt
    End Function
    'It will take records from the form and save it in the table if there is any problem then it will return false else it will return true
    Function Insertdata(ByVal dt As DataTable) As Boolean
        Dim cmd As New OleDbCommand
        Dim i As Integer
        Dim flag As Boolean = False

        For i = 0 To dt.Rows.Count - 1
            cmd = New OleDbCommand
            str = New System.Text.StringBuilder
            'Str will create the whole insert statement.

            str.Append("insert into studentdetails values (")
            str.Append(dt.Rows(i).Item(0))
            str.Append(",'")
            str.Append(dt.Rows(i).Item(1))
            str.Append("','")
            str.Append(dt.Rows(i).Item(2))
            str.Append("',")
            str.Append(dt.Rows(i).Item(3))
            str.Append(")")
            cmd.Connection = con
            cmd.CommandType = CommandType.Text
            cmd.CommandText = str.ToString

            'ExecuteNonQuery will return true if it will effect the table or will return false
            If cmd.ExecuteNonQuery() Then
                flag = True
            Else
                flag = False
                Exit For
            End If
            'Clearing the memory
            cmd = Nothing
            str = Nothing
        Next

        If flag = True Then
            Return True
        Else
            Return False

        End If
    End Function
End Class

'It will import the class that i have created.
Imports ThreetierAppl.Conn
Public Class Form1
    'Creating the object of conn class
    Dim obj As New Conn
    Dim dt As New DataTable
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        showdata()
        '     gv.Sort(gv.Columns(1), System.ComponentModel.ListSortDirection.Descending)
    End Sub
    Sub showdata()
        'Creating the column checkbox column in datatable
        Dim col As New DataColumn
        col.Caption = "Check"
        col.DataType = System.Type.GetType("System.Boolean")
        col.DefaultValue = False
        dt = obj.SelectData("studentdetails")
        dt.Columns.Add(col)
        gv.DataSource = dt
        gv.Columns(4).DisplayIndex = (0)
        gv.Columns(4).HeaderText = "Select"

    End Sub

    Private Sub Insert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Insert.Click
        Dim dt1 As New DataTable
        'Dt1 will have all the new records that are added from the user.
        dt1 = dt.GetChanges(DataRowState.Added)
        'It will call the insertdata method of conn class and will return true or false.
        If obj.Insertdata(dt1) Then
            MsgBox("Data inserted")
        Else
            MsgBox("Error in insertion")
        End If
    End Sub
End Class