How to Filter Data in the DataGridview Using CheckBoxes in VB.Net

CREATE TABLE `tblperson` (
  `PersonID` int(11) NOT NULL,
  `Fullname` varchar(90) NOT NULL,
  `CivilStatus` varchar(30) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
 
--
-- Dumping data for table `tblperson`
--
 
INSERT INTO `tblperson` (`PersonID`, `Fullname`, `CivilStatus`) VALUES
(1, 'Janobe Sourcecode', 'Single'),
(2, 'Mark Lim', 'Married'),
(3, 'Jake Cueca', 'Widow');

 
using MySql.Data.MySqlClient;

 
    Dim con As MySqlConnection = New MySqlConnection("server=localhost;user id =root;password=;database=tuts_persondb;sslMode=none")
    Dim cmd As MySqlCommand
    Dim da As MySqlDataAdapter
    Dim dt As DataTable
    Dim sql As String = ""
    Dim stat_single As String = ""
    Dim stat_married As String = ""
    Dim stat_widow As String = "" 

 
    Private Sub loadData(sql As String)
        Try
            con.Open()
            cmd = New MySqlCommand
            da = New MySqlDataAdapter
            dt = New DataTable
 
            With cmd
                .Connection = con
                .CommandText = sql
            End With
 
            da.SelectCommand = cmd
            da.Fill(dt)
 
            DataGridView1.DataSource = dt
 
        Catch ex As Exception
            MsgBox(ex.Message)
        Finally
            con.Close()
            da.Dispose()
        End Try
    End Sub 

 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        sql = "SELECT * FROM `tblperson`"
        loadData(sql)
    End Sub

 
    Private Sub chkSingle_CheckedChanged(sender As Object, e As EventArgs) Handles chkSingle.CheckedChanged, chkMarried.CheckedChanged, chkWidow.CheckedChanged
 
 
        If chkSingle.Checked Then
            stat_single = chkSingle.Text
        End If
 
        If chkMarried.Checked Then
            stat_married = chkMarried.Text
        End If
 
        If chkWidow.Checked Then
            stat_widow = chkWidow.Text
        End If
 
 
        sql = "SELECT * FROM `tblperson` WHERE `CivilStatus` in ('" & stat_single & "','" & stat_married & "','" & stat_widow & "')"
        loadData(sql)
 
    End Sub