i got the some error

Question

protected void Page_Load(object sender, EventArgs e)

{

string r = @"server=.;database=romesh;trusted_connecton=true";

SqlConnection con = new SqlConnection(r);

}

protected void btn_insert_Click(object sender, EventArgs e)

{

string i= "insert into sample values('"+txt1.Text+"','"+txt2.Text+"','"+txt3.Text+"')";

con.open();

SqlCommand cmd = con.createcommend();

cmd.CommandType = CommandType.Text;

cmd.CommandText = "i";

cmd.EndExecuteNonQuery();

con.close();

}

}

// I will get the error my code