ADO Net C# Tutorial

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.OracleClient;
  public class Form1 : System.Windows.Forms.Form
  {
    private System.Windows.Forms.Button btnConnect;
    private System.Windows.Forms.Button btnGetIDs;
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.ComboBox cbEmpIds;
    private System.Windows.Forms.Label lblFirstName;
    private System.Windows.Forms.Label lblLastName;
    private System.Windows.Forms.Label label4;
    private System.Windows.Forms.Label label5;
    private System.Windows.Forms.Button btnLookup1;
    private System.Windows.Forms.Button btnLookup2;
    private System.Windows.Forms.Label lblEmail;
    private System.Windows.Forms.Label lblPhone;
    private System.Windows.Forms.Label lblEmailText;
    private System.Windows.Forms.Label lblPhoneText;
    private System.Windows.Forms.Button btnReset;
    private System.Windows.Forms.Button btnNoBinds;
    private System.Data.OracleClient.OracleConnection oraConn;
    private System.Data.OracleClient.OracleCommand cmdGetIDs;
    private System.Data.OracleClient.OracleCommand cmdLookup1;
    private System.Data.OracleClient.OracleCommand cmdLookup2;
    private System.Data.OracleClient.OracleCommand cmdNoBinds1;
    private System.Data.OracleClient.OracleCommand cmdNoBinds2;
    public Form1()
    {
      this.btnConnect = new System.Windows.Forms.Button();
      this.btnGetIDs = new System.Windows.Forms.Button();
      this.cbEmpIds = new System.Windows.Forms.ComboBox();
      this.label1 = new System.Windows.Forms.Label();
      this.lblFirstName = new System.Windows.Forms.Label();
      this.lblLastName = new System.Windows.Forms.Label();
      this.label4 = new System.Windows.Forms.Label();
      this.label5 = new System.Windows.Forms.Label();
      this.btnLookup1 = new System.Windows.Forms.Button();
      this.btnLookup2 = new System.Windows.Forms.Button();
      this.lblEmail = new System.Windows.Forms.Label();
      this.lblPhone = new System.Windows.Forms.Label();
      this.lblEmailText = new System.Windows.Forms.Label();
      this.lblPhoneText = new System.Windows.Forms.Label();
      this.btnReset = new System.Windows.Forms.Button();
      this.btnNoBinds = new System.Windows.Forms.Button();
      this.oraConn = new System.Data.OracleClient.OracleConnection();
      this.cmdGetIDs = new System.Data.OracleClient.OracleCommand();
      this.cmdLookup1 = new System.Data.OracleClient.OracleCommand();
      this.cmdLookup2 = new System.Data.OracleClient.OracleCommand();
      this.cmdNoBinds1 = new System.Data.OracleClient.OracleCommand();
      this.cmdNoBinds2 = new System.Data.OracleClient.OracleCommand();
      this.SuspendLayout();
      this.btnConnect.Location = new System.Drawing.Point(32, 44);
      this.btnConnect.Text = "C&onnect";
      this.btnConnect.Click += new System.EventHandler(this.btnConnect_Click);
      this.btnGetIDs.Location = new System.Drawing.Point(32, 80);
      this.btnGetIDs.Text = "&Get IDs";
      this.btnGetIDs.Click += new System.EventHandler(this.btnGetIDs_Click);
      this.cbEmpIds.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
      this.cbEmpIds.Location = new System.Drawing.Point(144, 44);
      this.cbEmpIds.Size = new System.Drawing.Size(68, 21);
      this.label1.Location = new System.Drawing.Point(144, 24);
      this.label1.Size = new System.Drawing.Size(72, 16);
      this.label1.Text = "&Employee ID:";
      this.lblFirstName.Location = new System.Drawing.Point(228, 48);
      this.lblFirstName.Size = new System.Drawing.Size(116, 16);
      this.lblLastName.Location = new System.Drawing.Point(364, 48);
      this.lblLastName.Size = new System.Drawing.Size(128, 16);
      this.label4.Location = new System.Drawing.Point(228, 24);
      this.label4.Size = new System.Drawing.Size(100, 16);
      this.label4.Text = "&First Name:";
      this.label5.Location = new System.Drawing.Point(364, 24);
      this.label5.Size = new System.Drawing.Size(100, 16);
      this.label5.Text = "&Last Name:";
      this.btnLookup1.Location = new System.Drawing.Point(32, 116);
      this.btnLookup1.Text = "Lookup &1";
      this.btnLookup1.Click += new System.EventHandler(this.btnLookup1_Click);
      this.btnLookup2.Location = new System.Drawing.Point(32, 152);
      this.btnLookup2.Text = "Lookup &2";
      this.btnLookup2.Click += new System.EventHandler(this.btnLookup2_Click);
      this.lblEmail.Location = new System.Drawing.Point(228, 88);
      this.lblEmail.Size = new System.Drawing.Size(100, 16);
      this.lblEmail.Text = "E&mail:";
      this.lblPhone.Location = new System.Drawing.Point(364, 88);
      this.lblPhone.Size = new System.Drawing.Size(100, 16);
      this.lblPhone.Text = "Phone &Number:";
      this.lblEmailText.Location = new System.Drawing.Point(228, 112);
      this.lblEmailText.Size = new System.Drawing.Size(116, 16);
      this.lblPhoneText.Location = new System.Drawing.Point(364, 112);
      this.lblPhoneText.Size = new System.Drawing.Size(128, 16);
      this.btnReset.Location = new System.Drawing.Point(32, 224);
      this.btnReset.Text = "&Reset";
      this.btnReset.Click += new System.EventHandler(this.btnReset_Click);
      this.btnNoBinds.Location = new System.Drawing.Point(32, 188);
      this.btnNoBinds.Text = "No &Binds";
      this.btnNoBinds.Click += new System.EventHandler(this.btnNoBinds_Click);
      this.oraConn.ConnectionString = "user id=hr;data source=oranet;password=demo";
      this.cmdGetIDs.CommandText = "SELECT EMPLOYEE_ID FROM EMPLOYEES ORDER BY EMPLOYEE_ID";
      this.cmdGetIDs.Connection = this.oraConn;
      this.cmdLookup1.CommandText = "SELECT FIRST_NAME, LAST_NAME FROM EMPLOYEES WHERE (EMPLOYEE_ID = :p_id)";
      this.cmdLookup1.Connection = this.oraConn;
      this.cmdLookup1.Parameters.Add(new System.Data.OracleClient.OracleParameter(":p_id", System.Data.OracleClient.OracleType.Number, 0, System.Data.ParameterDirection.Input, false, ((System.Byte)(6)), ((System.Byte)(0)), "EMPLOYEE_ID", System.Data.DataRowVersion.Current, null));
      this.cmdLookup2.CommandText = "SELECT EMAIL, PHONE_NUMBER FROM EMPLOYEES WHERE (FIRST_NAME = :p_first) AND (LAST" +
        "_NAME = :p_last)";
      this.cmdLookup2.Connection = this.oraConn;
      this.cmdLookup2.Parameters.Add(new System.Data.OracleClient.OracleParameter(":p_first", System.Data.OracleClient.OracleType.VarChar, 20, "FIRST_NAME"));
      this.cmdLookup2.Parameters.Add(new System.Data.OracleClient.OracleParameter(":p_last", System.Data.OracleClient.OracleType.VarChar, 25, "LAST_NAME"));
      this.cmdNoBinds1.Connection = this.oraConn;
      this.cmdNoBinds2.Connection = this.oraConn;
      this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
      this.ClientSize = new System.Drawing.Size(534, 264);
      this.Controls.Add(this.btnNoBinds);
      this.Controls.Add(this.btnReset);
      this.Controls.Add(this.lblPhoneText);
      this.Controls.Add(this.lblEmailText);
      this.Controls.Add(this.lblPhone);
      this.Controls.Add(this.lblEmail);
      this.Controls.Add(this.btnLookup2);
      this.Controls.Add(this.btnLookup1);
      this.Controls.Add(this.label5);
      this.Controls.Add(this.label4);
      this.Controls.Add(this.lblLastName);
      this.Controls.Add(this.lblFirstName);
      this.Controls.Add(this.label1);
      this.Controls.Add(this.cbEmpIds);
      this.Controls.Add(this.btnGetIDs);
      this.Controls.Add(this.btnConnect);
      this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.Fixed3D;
      this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
      this.Load += new System.EventHandler(this.Form1_Load);
      this.ResumeLayout(false);
    }
    static void Main() 
    {
      Application.Run(new Form1());
    }
    private void btnConnect_Click(object sender, System.EventArgs e)
    {
      if (oraConn.State != ConnectionState.Open)
      {
         oraConn.Open();
         MessageBox.Show(oraConn.ConnectionString, "Successful Connection");
      }
    }
    private void btnGetIDs_Click(object sender, System.EventArgs e)
    {
        OracleDataReader dataReader = cmdGetIDs.ExecuteReader();
        while (dataReader.Read())
        {
          cbEmpIds.Items.Add(dataReader.GetDecimal(0));
        }
    }
    private void Form1_Load(object sender, System.EventArgs e)
    {
    }
    private void btnLookup1_Click(object sender, System.EventArgs e)
    {
      object selectedItem = cbEmpIds.SelectedItem;
      if (selectedItem != null)
      {
        cmdLookup1.Parameters[0].Value = Convert.ToDecimal(selectedItem.ToString());
        OracleDataReader dataReader = cmdLookup1.ExecuteReader();
        if (dataReader.Read())
        {
          lblFirstName.Text = dataReader.GetString(0);
          lblLastName.Text = dataReader.GetString(1);
        }
        dataReader.Close();
        dataReader.Dispose();
      }
    }
    private void btnLookup2_Click(object sender, System.EventArgs e)
    {
      cmdLookup2.Parameters[0].Value = lblFirstName.Text;
      cmdLookup2.Parameters[1].Value = lblLastName.Text;
      OracleDataReader dataReader = cmdLookup2.ExecuteReader();
      if (dataReader.Read())
      {
        lblEmailText.Text = dataReader.GetString(0);
        lblPhoneText.Text = dataReader.GetString(1);
      }
      dataReader.Close();
      dataReader.Dispose();
    }
    private void btnReset_Click(object sender, System.EventArgs e)
    {
      cbEmpIds.SelectedIndex = -1;
      lblFirstName.Text = "";
      lblLastName.Text = "";
      lblEmailText.Text = "";
      lblPhoneText.Text = "";
    }
    private void btnNoBinds_Click(object sender, System.EventArgs e)
    {
      object selectedItem = cbEmpIds.SelectedItem;
      if (selectedItem != null)
      {
        OracleDataReader dataReader;
        cmdNoBinds1.CommandText = "select first_name, last_name from employees where employee_id = " + selectedItem.ToString();
        dataReader = cmdNoBinds1.ExecuteReader();
        if (dataReader.Read())
        {
          lblFirstName.Text = dataReader.GetString(0);
          lblLastName.Text = dataReader.GetString(1);
        }
        dataReader.Close();
        cmdNoBinds2.CommandText = "select email, phone_number from employees where first_name = '" + lblFirstName.Text + "' and last_name = '" + lblLastName.Text +"'";
        dataReader = cmdNoBinds2.ExecuteReader();
        if (dataReader.Read())
        {
          lblEmailText.Text = dataReader.GetString(0);
          lblPhoneText.Text = dataReader.GetString(1);
        }
        dataReader.Close();
        dataReader.Dispose();
      }
    }
  }