Update SQL Table Thro C#

using System.Data.OleDb;


 public OleDbConnection cn = new OleDbConnection(@"provider= sqloledb; Data Source=nameofserver\SQLEXPRESS;Initial Catalog=DataBase;Persist Security Info=True;User ID=userid;Password=pwd");
       


on buttonclick-----------


cn.Open();
            OleDbCommand cmd = new OleDbCommand();
            cmd.Connection = cn;
            cmd.CommandText = "update  diarydata set SrNo=?Diary=?,CreatedDate=? where SrNo="+txtSrNo.Text+"";      
            cmd.Parameters.Add("@SrNo", OleDbType.Numeric).Value = int.Parse(textBox1).Text;
            cmd.Parameters.Add("@DiaryData", OleDbType.VarChar).Value = richTextBox1.Text;
            cmd.Parameters.Add("@CeratedDate", OleDbType.Date).Value = dateTimePicker1.Value; 
            cmd.ExecuteReader();
            MessageBox.Show("Data updated");
            cn.Close();