ASP.NET 4 Unleased - p 41 potx

You can connect to a Local database named MyLocalData.mdf by using the following connection string: Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|MyLocalData.mdf; Integrated S

When you click Add, Visual Web Developer warns you that it needs to create the

App_Data folder (if the folder doesn’t already exist) The MyLocalData.mdf file will be

added to this folder Click OK to create the new folder

You can connect to a Local database named MyLocalData.mdf by using the following

connection string:

Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|MyLocalData.mdf;

Integrated Security=True;User Instance=True

When you connect to the MyLocalData.mdf file, the database is attached automatically to

Microsoft SQL Server Express

The connection string includes an AttachDbFilename parameter This parameter represents

the physical path to a database file (.mdf file) The keyword |DataDirectory| is used in

the path The |DataDirectory| keyword represents a website’s App_Data folder

Instead of using the |DataDirectory| keyword, you could supply the entire physical path

to a database file The advantage of using the |DataDirectory| keyword is that you can

move your web application easily to a new location without needing to change the

connection string

The connection string also includes a User Instance parameter Creating a User Instance

connection enables you to connect to a Local database without using an Administrator

account Because the ASPNET account is not an Administrator account, you need to add

this parameter to use Local databases from ASP.NET pages

Including the User Instance parameter in a connection string causes a separate user

instance of SQL Server to execute with the security context of the user The first time a

user creates a User Instance connection, copies of the system databases are copied to a

user’s application data folder located at the following path:

C:\Users\[Username]\AppData\Local\Microsoft\Microsoft SQL Server Data\SQLEXPRESS

A separate set of system databases is created for each user

NOTE

By default, when a page is served from Internet Information Server, the page executes

in the security context of either the ASPNET or Network Service account When a page

is served from the web server included in Visual Web Developer, the page executes in

the security context of the current user

One of the primary advantages of using a Local database rather than a Server database is

that a Local database can be moved easily to a new location If you email a Local database

file (the mdf file stored in the App_Data folder) to a friend, your friend can start using the

database immediately The only requirement is that your friend has SQL Server Express

installed on a computer

Sample Database-Driven Web Application

The following chapters get into all the gritty details of the Data controls Before you get

lost in the details, however, I want to provide you with a sample of a data-driven web

application I want to provide you with a real-world application that illustrates what can

be built with the Data controls

In this section, a complete Employee Directory application is built, which supports

displaying, adding, editing, and deleting employee information The sample application

includes all the necessary form field validation

One of the amazing things about ASP.NET 4 Framework is how much the Framework

simplifies data access The sample application consists of a single page that contains little

code Writing the same application with ASP.NET 1.x Framework would require pages of

code (I won’t even mention how much code it would require to write the same

applica-tion in ASP Classic.)

Because the Employee Directory application includes all the required validation code, the

page is a little too long to include in the pages of this book However, it is included on the

book’s website Open the page named EmployeeDirectory.aspx

After you open the EmployeeDirectory.aspx page in your browser, you see a list of

employees This list is rendered by a GridView control (see Figure 8.18)

FIGURE 8.18 Displaying a list of employees with the GridView control

Next to each employee, there is a Delete link and a Details link If you click Delete, the

selected employee is deleted from the database A client-side confirmation dialog box

appears when you click the Delete link (see Figure 8.19) This dialog box is added to each

of the Delete links in the grdEmployees_RowCreated() method This method is called

automatically by the GridView control as the GridView creates each row

FIGURE 8.19 Deleting employee information

If you click the Details link, a window appears that displays detailed information for the

Employee (see Figure 8.20) The detailed information is rendered by a FormView control

The window that appears is created with an absolutely positioned <div> tag

If you click Edit when viewing a employee’s details, you can edit the employee record The

edit form is contained in the FormView control’s EditItemTemplate Each of the form fields

is associated with a RequiredFieldValidator control

Finally, you can add new employees to the directory by clicking the Add Employee

button The form that appears is also rendered by a FormView control (see Figure 8.21)

WEB STANDARDS NOTE

The Employee Directory application works great in Internet Explorer 6+, Firefox 1.0+,

and Opera 8.0+ The only feature of the application that breaks Web standards is the

use of the Drop Shadow filter around the pop-up window The Drop Shadow effect

works only in Internet Explorer

FIGURE 8.20 Displaying employee details

FIGURE 8.21 Adding a new employee

Summary

In this chapter, you were provided with an overview of the Data controls included in the

ASP.NET 4 Framework You learned how to use the DataBound controls to render the user

interface for working with data You also were provided with an introduction to the

DataSource controls, which can be used to represent different types of data such as

data-base data and XML data

You also learned about two important features of the DataBound controls You learned how

to use Templates and databinding expressions You learned about the difference between

one-way databinding and two-way databinding expressions

Next, you were provided with an overview of SQL Server 2008 Express You learned how

to create a SQL Server Express database You also learned how to create both Server and

Local databases

Finally, the Data controls were used to build a sample application: the Employee Directory

application You learned how to use the controls to build an application that enables you

to list, edit, insert, and delete database records

Using the SqlDataSource

Control

Creating Database Connections Executing Database Commands Using ASP.NET Parameters with the SqlDataSource Control Programmatically Executing SqlDataSource Commands Caching Database Data with the SqlDataSource Control Summary

The SqlDataSource control enables you to quickly and

easily represent a SQL database in a web page In many

cases, you can take advantage of the SqlDataSource control

to write a database-driven web page without writing a single

line of code

You use the SqlDataSource control to represent a

connec-tion and set of commands that can be executed against a

SQL database You can use the SqlDataSource control when

working with Microsoft SQL Server, Microsoft SQL Server

Express, Microsoft Access, Oracle, DB2, MySQL, or just about

any other SQL relational database ever created by man

NOTE

Although you can use the SqlDataSource control

when working with Microsoft Access, the ASP.NET

Framework does include the AccessDataSource

con-trol, which was designed specifically for Microsoft

Access Because using Microsoft Access for a website

is not recommended, this book doesn’t discuss the

AccessDataSource control

The SqlDataSource control is built on top of ADO.NET

Under the covers, the SqlDataSource uses ADO.NET objects

such as the DataSet, DataReader, and Command objects

Because the SqlDataSource control is a control, it enables

you to use these ADO.NET objects declaratively rather than

programmatically

The SqlDataSource control is a nonvisual control—it doesn’t render anything You use the

SqlDataSource control with other controls, such as the GridView or FormView controls, to

display and edit database data The SqlDataSource control can also be used to issue SQL

commands against a database programmatically

NOTE

The SqlDataSource control is not an appropriate control to use when building more

complicated multitier applications The SqlDataSource control forces you to mix your

data access layer with your user interface layer If you want to build a more cleanly

architected multi-tier application, you should use the ObjectDataSource control to

represent your database data

The ObjectDataSource is discussed in detail in Chapter 18, “Using the

ObjectDataSource Control.”

In this chapter, you learn how to represent connections and commands with the

SqlDataSource control You also learn how to use different types of parameters when

executing commands Finally, you learn how to improve the performance of your

database-driven applications by taking advantage of the SqlDataSource control’s support

for caching database data

Creating Database Connections

You can use the SqlDataSource control to connect to just about any SQL relational

data-base server In this section, you learn how to connect to Microsoft SQL Server and other

databases such as Oracle You also learn how you can store the database connection string

used by SqlDataSource securely in your web configuration files

Connecting to Microsoft SQL Server

By default, the SqlDataSource control is configured to connect to Microsoft SQL Server

version 7.0 or higher The default provider used by the SqlDataSource control is the

ADO.NET provider for Microsoft SQL Server

You represent a database connection string with the SqlDataSource control’s

ConnectionString property For example, the page in Listing 9.1 includes a SqlDataSource

control that connects to a local SQL Server 2008 database (see Figure 9.1)

LISTING 9.1 ShowLocalConnection.aspx

<%@ Page Language=”C#” %>

<!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 id=”Head1” runat=”server”>

<title>Show Local Connection</title>

</head>

<body>

<form id=”form1” runat=”server”>

<div>

<asp:GridView

id=”grdMovies”

DataSourceID=”srcMovies”

Runat=”server” />

<asp:SqlDataSource

id=”srcMovies”

SelectCommand=”SELECT * FROM Movies”

ConnectionString=”Data Source=.\SQLEXPRESS;

AttachDbFilename=|DataDirectory|MyDatabase.mdf;

FIGURE 9.1 Displaying the Movies database table

Integrated Security=True;User Instance=True”

Runat=”server” />

</div>

</form>

</body>

</html>

In Listing 9.1, the SqlDataSource control uses the following connection string:

Data Source=.\SQLEXPRESS;

AttachDbFilename=|DataDirectory|MyDatabase.mdf;

Integrated Security=True;User Instance=True

This connection string connects to an instance of SQL Server Express located on the local

machine and a database file named MyDatabase.mdf The connection string uses

Integrated Security (a Trusted Connection) to connect to the local database

You can use the following connection string to connect to a database located on a

remote server

Data Source=DataServer;Initial Catalog=Northwind;

User ID=webuser;Password=secret

This database connection string connects to a SQL Server database located on a remote

machine named DataServer The connection string connects to a database named

Northwind

This second connection string uses SQL Standard Security instead of Integrated Security It

contains a user ID and password associated with a SQL Server login

WARNING

For security reasons, you should never include a connection string that contains

securi-ty credentials in an ASP.NET page Theoretically, no one should see the source of an

ASP.NET page However, Microsoft does not have a perfect track record Later in this

section, you learn how to store connection strings in the web configuration file (and

encrypt them)

The NET Framework includes a utility class, named the SqlConnectionBuilder class, that

you can use when working with SQL connection strings This class automatically converts

any connection string into a canonical representation It also exposes properties for

extracting and modifying individual connection string parameters, such as the Password

parameters

For example, the page in Listing 9.2 automatically converts any connection string into its

canonical representation (see Figure 9.2)

LISTING 9.2 SqlConnectionStringBuilder.aspx

<%@ Page Language=”C#” %>

<%@ Import Namespace=”System.Data.SqlClient” %>

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN”

“http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”>

<script runat=”server”>

protected void btnConvert_Click(object sender, EventArgs e)

{

SqlConnectionStringBuilder builder = new

SqlConnectionStringBuilder(txtConnectionString.Text);

lblResult.Text = builder.ConnectionString;

}

</script>

<html xmlns=”http://www.w3.org/1999/xhtml” >

<head id=”Head1” runat=”server”>

<title>SQL Connection String Builder</title>

</head>

FIGURE 9.2 Converting a connection string