Define data layer in a separate class : SqlConnection « ADO.net Database « ASP.NET Tutorial






<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="ComponentTest" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <h2>Employees</h2>
      <asp:Literal runat="server" ID="HtmlContent" />
    </div>
    </form>
</body>
</html>

File: Default.aspx.cs

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text;
using System.Data.SqlClient;
using System.Web.Configuration;

public partial class ComponentTest : System.Web.UI.Page
{

  private EmployeeDB db = new EmployeeDB();

  protected void Page_Load(object sender, System.EventArgs e)
  {
    WriteEmployeesList();

    int empID = db.InsertEmployee(
      new EmployeeDetails(0, "Mr.", "Bellinaso", "Marco"));
    HtmlContent.Text += "<br>Inserted 1 employee.<br>";

    WriteEmployeesList();

    db.DeleteEmployee(empID);
    HtmlContent.Text += "<br>Deleted 1 employee.<br>";

    WriteEmployeesList();
  }


  private void WriteEmployeesList()
  {
    StringBuilder htmlStr = new StringBuilder("");

    int numEmployees = db.CountEmployees();
    htmlStr.Append("<br>Total employees: <b>");
    htmlStr.Append(numEmployees.ToString());
    htmlStr.Append("</b><br><br>");

    EmployeeDetails[] employees = db.GetEmployees();
    foreach (EmployeeDetails emp in employees)
    {
      htmlStr.Append("<li>");
      htmlStr.Append(emp.EmployeeID);
      htmlStr.Append(" ");
      htmlStr.Append(emp.TitleOfCourtesy);
      htmlStr.Append(" <b>");
      htmlStr.Append(emp.FirstName);
      htmlStr.Append("</b>, ");
      htmlStr.Append(emp.LastName);
      htmlStr.Append("</li>");
    }
    htmlStr.Append("<br>");
    HtmlContent.Text += htmlStr.ToString();
  }
}

public class EmployeeDetails
{
  private int employeeID;
  private string firstName;
  private string lastName;
  private string titleOfCourtesy;

  public int EmployeeID
  {
    get {return employeeID;}
    set {employeeID = value;}
  }
  public string FirstName
  {
    get {return firstName;}
    set {firstName = value;}
  }
  public string LastName
  {
    get {return lastName;}
    set {lastName = value;}
  }
  public string TitleOfCourtesy
  {
    get {return titleOfCourtesy;}
    set {titleOfCourtesy = value;}
  }

  public EmployeeDetails(int employeeID, string firstName, string lastName,
    string titleOfCourtesy)
  {
    this.employeeID = employeeID;
    this.firstName = firstName;
    this.lastName = lastName;
    this.titleOfCourtesy = titleOfCourtesy;
  }

  public EmployeeDetails(){}
}



public class EmployeeDB
{
  private string connectionString;

  public EmployeeDB()
  {
    connectionString = WebConfigurationManager.ConnectionStrings["Northwind"].ConnectionString;
  }
  public EmployeeDB(string connectionString)
  {
    this.connectionString = connectionString;
  }

  public int InsertEmployee(EmployeeDetails emp)
  {
    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand("InsertEmployee", con);
    cmd.CommandType = CommandType.StoredProcedure;

    cmd.Parameters.Add(new SqlParameter("@FirstName", SqlDbType.NVarChar, 10));
    cmd.Parameters["@FirstName"].Value = emp.FirstName;
    cmd.Parameters.Add(new SqlParameter("@LastName", SqlDbType.NVarChar, 20));
    cmd.Parameters["@LastName"].Value = emp.LastName;
    cmd.Parameters.Add(new SqlParameter("@TitleOfCourtesy", SqlDbType.NVarChar, 25));
    cmd.Parameters["@TitleOfCourtesy"].Value = emp.TitleOfCourtesy;
    cmd.Parameters.Add(new SqlParameter("@EmployeeID", SqlDbType.Int, 4));
    cmd.Parameters["@EmployeeID"].Direction = ParameterDirection.Output;
  
    try 
    {
      con.Open();
      cmd.ExecuteNonQuery();
      return (int)cmd.Parameters["@EmployeeID"].Value;
    }
    catch (SqlException err) 
    {
      throw new ApplicationException("Data error.");
    }
    finally 
    {
      con.Close();      
    }
  }


  public void UpdateEmployee(EmployeeDetails emp)
  {
    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand("UpdateEmployee", con);
    cmd.CommandType = CommandType.StoredProcedure;

    cmd.Parameters.Add(new SqlParameter("@FirstName", SqlDbType.NVarChar, 10));
    cmd.Parameters["@FirstName"].Value = emp.FirstName;
    cmd.Parameters.Add(new SqlParameter("@LastName", SqlDbType.NVarChar, 20));
    cmd.Parameters["@LastName"].Value = emp.LastName;
    cmd.Parameters.Add(new SqlParameter("@TitleOfCourtesy", SqlDbType.NVarChar, 25));
    cmd.Parameters["@TitleOfCourtesy"].Value = emp.TitleOfCourtesy;
    cmd.Parameters.Add(new SqlParameter("@EmployeeID", SqlDbType.Int, 4));
    cmd.Parameters["@EmployeeID"].Value = emp.EmployeeID;

    try
    {
      con.Open();
      cmd.ExecuteNonQuery();
    }
    catch (SqlException err)
    {
      throw new ApplicationException("Data error.");
    }
    finally
    {
      con.Close();
    }
  }

  public void UpdateEmployee(int EmployeeID, string firstName, string lastName, string titleOfCourtesy)
  {
    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand("UpdateEmployee", con);
    cmd.CommandType = CommandType.StoredProcedure;

    cmd.Parameters.Add(new SqlParameter("@FirstName", SqlDbType.NVarChar, 10));
    cmd.Parameters["@FirstName"].Value = firstName;
    cmd.Parameters.Add(new SqlParameter("@LastName", SqlDbType.NVarChar, 20));
    cmd.Parameters["@LastName"].Value = lastName;
    cmd.Parameters.Add(new SqlParameter("@TitleOfCourtesy", SqlDbType.NVarChar, 25));
    cmd.Parameters["@TitleOfCourtesy"].Value = titleOfCourtesy;
    cmd.Parameters.Add(new SqlParameter("@EmployeeID", SqlDbType.Int, 4));
    cmd.Parameters["@EmployeeID"].Value = EmployeeID;

    try
    {
      con.Open();
      cmd.ExecuteNonQuery();
    }
    catch (SqlException err)
    {
      throw new ApplicationException("Data error.");
    }
    finally
    {
      con.Close();
    }
  }

  public void DeleteEmployee(int employeeID)
  {
    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand("DeleteEmployee", con);
    cmd.CommandType = CommandType.StoredProcedure;

    cmd.Parameters.Add(new SqlParameter("@EmployeeID", SqlDbType.Int, 4));
    cmd.Parameters["@EmployeeID"].Value = employeeID;
      
    try 
    {
      con.Open();
      cmd.ExecuteNonQuery();
    }
    catch (SqlException err) 
    {
      throw new ApplicationException("Data error.");
    }
    finally 
    {
      con.Close();      
    }
  }

  public EmployeeDetails GetEmployee(int employeeID)
  {
    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand("GetEmployee", con);
    cmd.CommandType = CommandType.StoredProcedure;

    cmd.Parameters.Add(new SqlParameter("@EmployeeID", SqlDbType.Int, 4));
    cmd.Parameters["@EmployeeID"].Value = employeeID;
        
    try 
    {
      con.Open();
      SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.SingleRow);
      
      reader.Read();
      EmployeeDetails emp = new EmployeeDetails(
        (int)reader["EmployeeID"], (string)reader["FirstName"],
        (string)reader["LastName"], (string)reader["TitleOfCourtesy"]);
      reader.Close();
      return emp;
    }
    catch (SqlException err) 
    {
      throw new ApplicationException("Data error.");
    }
    finally 
    {
      con.Close();      
    }
  }

  public EmployeeDetails[] GetEmployees()
  {
    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand("GetAllEmployees", con);
    cmd.CommandType = CommandType.StoredProcedure;
        
    ArrayList employees = new ArrayList();

    try 
    {
      con.Open();
      SqlDataReader reader = cmd.ExecuteReader();

      while (reader.Read())
      {
        EmployeeDetails emp = new EmployeeDetails(
          (int)reader["EmployeeID"], (string)reader["FirstName"],
          (string)reader["LastName"], (string)reader["TitleOfCourtesy"]);
        employees.Add(emp);
      }
      reader.Close();
      
      return (EmployeeDetails[])employees.ToArray(typeof(EmployeeDetails));
    }
    catch (SqlException err) 
    {
      throw new ApplicationException("Data error.");
    }
    finally 
    {
      con.Close();      
    }
  }
      
  public int CountEmployees()
  {
    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand("CountEmployees", con);
    cmd.CommandType = CommandType.StoredProcedure;
        
    try 
    {
      con.Open();
      return (int)cmd.ExecuteScalar();
    }
    catch (SqlException err) 
    {
      throw new ApplicationException("Data error.");
    }
    finally 
    {
      con.Close();      
    }
  }
}

File: Web.config

<?xml version="1.0"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
  <connectionStrings>
    <add name="Northwind" connectionString= "Data Source=localhost;Initial Catalog=Northwind;Integrated Security=SSPI"/>
  </connectionStrings>
  <system.web>
    <compilation debug="true"/>
    <authentication mode="Windows"/>
  </system.web>
</configuration>








18.2.SqlConnection
18.2.1.Retrieving Provider Statistics about the database commands executed with the connection
18.2.2.Displaying all provider statistics.
18.2.3.Improving Performance with Connection Pooling
18.2.4.Define data layer in a separate class
18.2.5.Hard code connection string in DropDownList