VB.net program to insert,update,delete,display Data using the SQL server

Imports System.Data.SqlClient
Public Class Form1
    Dim conn As SqlConnection
    Dim cmd As SqlCommand
    Dim dr As SqlDataReader




    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        conn = New SqlConnection("Data Source=DESKTOP-TQDE2RV\SQLEXPR<Server>;Initial Catalog=trail;Integrated Security=True")

    End Sub



    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        conn.Open()
        Dim q1 As String = "insert into samp(name,ph)values('" + TextBox1.Text + "','" + TextBox2.Text + "')"

'samp is the table name

        cmd = New SqlCommand(q1, conn)
        cmd.ExecuteNonQuery()
        MessageBox.Show("inserted")
        conn.Close()
        TextBox1.Text = ""
        TextBox2.Text = ""
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        conn.Open()
        Dim q2 As String = "update samp set ph='" + TextBox2.Text + "' where name='" + TextBox1.Text + "'"
        cmd = New SqlCommand(q2, conn)
        cmd.ExecuteNonQuery()
        MessageBox.Show("updated")
        conn.Close()


    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        conn.Open()
        Dim q3 As String = "delete from samp where name='" + TextBox1.Text + "'"
        cmd = New SqlCommand(q3, conn)
        cmd.ExecuteNonQuery()
        MessageBox.Show("deleted")
        conn.Close()
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        conn.Open()
        Dim q4 As String = "select ph from samp where name='" + TextBox1.Text + "'"
        cmd = New SqlCommand(q4, conn)
        dr = cmd.ExecuteReader()
        While (dr.Read())
            TextBox2.Text = dr.Item("ph")
        End While

    End Sub
End Class