chapter 12: ado.net and asp.net programming with microsoft visual basic.net, second edition

Chapter 12: ADO.NET and ASP.NET

Programming with Microsoft Visual Basic .NET, Second Edition

Programming with Microsoft Visual Basic .NET, Second Edition 2

Database TerminologyLesson A Objectives

• Define the terms used when talking about databases

• Explain the purpose of the DataAdapter, Connection, and DataSet objects

• Explain the role of the provider

• Create and configure an OleDbDataAdapter object


Database TerminologyLesson A Objectives (continued)

• Write SQL SELECT statements

• Create a dataset

• Display a dataset in a DataGrid control


Database Terminology (continued)

• Database: organized collection of related information stored in a file on a disk

• Relational database: database that stores information in tables

– Each column represents a field

– Each row represents a record



• Table: a group of related records

• Each record in a table pertains to the same topic, and each contains the same type of information

• Relational database contains one or more tables

• Primary key: a field that uniquely identifies each record in a table



Figure 12-3: Example of a two-table relational database



• In Figure 12-3:

– The first table is called the parent table

– The second table is called the child table

– In the parent table, the Number field is the primary key

– In the child table, the Number field is called the foreign key


ADO.NET

• To connect an application to a database, Visual Basic .NET uses ADO.NET

• With ADO.NET, the connection between an application and a database is a temporary one

• Use three ADO.NET objects and a provider to access a database from a Visual Basic .NET application

– DataAdapter, Connection, and DataSet


ADO.NET (continued)

Figure 12-4: Illustration of the relationships among an application, the ADO.NET objects, a provider, and a database


Creating and Configuring a DataAdapter Object

• The DataAdapter object is the link between the application and the Connection object

• DataAdapter object contacts the Connection object whenever the application needs to read data from or write data to a database


Creating and Configuring a DataAdapter Object (continued)

Figure 12-6: Procedure for creating and configuring a DataAdapter object for a Microsoft Access database


Creating and Configuring a DataAdapter Object (continued)

Figure 12-6: Procedure for creating and configuring a DataAdapter object for a Microsoft Access database (continued)


SQL

• SQL (Structured Query Language): a set of commands to access and manipulate the data stored in many database management systems

• SQL commands perform database tasks such as storing, retrieving, updating, deleting, and sorting


SQL (continued)

• SELECT statement allows you to:

– Specify the fields and records you want to view

– Control the order in which the fields and records appear when displayed


SQL (continued)

Figure 12-13: Syntax and examples of the SELECT statement


SQL (continued)

Figure 12-13: Syntax and examples of the SELECT statement (continued)


Using the Query Builder to Enter a SELECT Statement

• When you click the Next > button on the Choose a Query Type screen, the Generate the SQL statements screen appears

• You can enter the SELECT statement yourself, or you can have the Query Builder enter it for you

• To use the Query Builder, click the Query Builder button

– The Query Builder and Add Table dialog boxes open


Using the Query Builder to Enter a SELECT Statement (continued)

Figure 12-15: Query Builder and Add Table dialog boxes


Using the Query Builder to Enter a SELECT Statement (continued)

Figure 12-18: SELECT statement entered in the Generate the SQL statements screen


Creating a Dataset

• A dataset contains the data you want to access from the database, as specified in the SELECT statement associated with the DataAdapter object

• XML (Extensible Markup Language): a text-based language used to store and share data between applications and across networks and the Internet

• An XML schema definition file defines the tables and fields that make up the dataset


Creating a Dataset (continued)

Figure 12-21: Procedure for creating a dataset


Using the Fill Method

• Use the DataAdapter object’s Fill method to fill a dataset with data while an application is running

Figure 12-25: Syntax and an example of the Fill method


Binding the DataSet Object to a DataGrid Control

• View the data contained in a dataset by connecting its DataSet object to one or more controls in the interface

• Binding: Connecting a DataSet object to a control

• Bound controls: the connected controls

• Bind a control using one or more properties listed in the Properties window


Binding the DataSet Object to a DataGrid Control (continued)

Figure 12-26: Procedure for binding a DataSet object to a DataGrid control


Binding the DataSet Object to a DataGrid Control (continued)

• When bound to a DataSet object, the DataGrid control displays the data from the dataset in a row and column format

– Each field in the dataset appears in a column in the DataGrid control

– Each record in the dataset appears in a row in the DataGrid control


Reconfiguring the DataAdapter Object

Figure 12-30: Procedure for reconfiguring an existing DataAdapter object


More on Binding ControlsLesson B Objectives

• Display a dataset in various controls in an interface

• Position the record pointer in a dataset


Binding the DataSet Object to a Label Control or a Text Box

Figure 12-33: Procedure for binding a DataSet object to a label control or text box


Coding the Cartwright Industries Application

• Carl Simons, the sales manager at Cartwright Industries, records the item number, name, and price of each product the company sells in a database named Items.mdb

• Items.mdb database

– Contains one table named tblItems

– The Number and Name fields contain text, and the Price field contains numbers


Coding the Cartwright Industries Application (continued)

Figure 12-37: Items.mdb database opened in Microsoft Access


Coding the Cartwright Industries Application (continued)

Figure 12-39: TOE chart for the Cartwright Industries application


Creating Web Applications Using ASP.NET

Lesson C Objectives

• Define the terms used when talking about the Web

• Create a Web application

• Add controls to a Web form

• Start a Web application


Creating Web Applications Using ASP.NET

Lesson C Objectives (continued)

• Use the validator controls

• Include a list box on a Web form

• Determine whether a postback has occurred

• Include a DataGrid control on a Web form


Web Terminology

• The Internet is the world’s largest computer network, connecting millions of computers located all around the world

• World Wide Web (WWW or the Web)

– Part of the Internet

– Consists of documents called Web pages that are stored on Web servers


Web Terminology (continued)

• Web server: computer that contains software that “serves up” Web pages in response to requests from clients

• A client is a computer that requests information from a Web server

• The information is requested and subsequently viewed through the use of a program called a Web browser (or simply, a browser)



Figure 12-49: Illustration of the relationship between a client, a browser, and a Web server



• Static Web page: document whose purpose is merely to display information to the viewer

• Dynamic Web page is interactive; it can accept information from the user and also retrieve information for the user

• Every Web page has a unique address called a URL (Uniform Resource Locator) that indicates its location on the Web


Creating Web Applications

• Use a Web form to create a Web page in Visual Basic .NET

• Create (or design) the Web page in the Web Form Designer window


Creating Web Applications (continued)

Figure 12-52: Procedure for creating a Web application


Adding Controls to a Web Form

• Use the tools contained in the Toolbox window to add controls to a Web form

• The tools for a Web form are located on the Web Forms tab in the toolbox

• Can add a control to a Web form by simply dragging the corresponding tool from the Web Forms tab to the form


Using the Web Validator Tools

• These tools allow you to validate user input

Figure 12-65: The Web validator tools


Including a List Box on a Web Form

• Use the ListBox tool on the Web Forms tab to add a list box to a Web form

• Can use a list box on a Web form to display a list of choices from which the user can select one or more choices


Including a List Box on a Web Form (continued)

• A postback refers to the client requesting data from the server, and the server responding

• Each time a postback occurs, the Web page is redisplayed on the client’s screen

• Can use the Web form’s IsPostBack property to determine if the Web form is being displayed for the first time or as a result of a postback


Including a DataGrid Control on a Web Form

• DataGrid control displays the data from a dataset in a row and column format

• Each field in the dataset appears in a column in the DataGrid control, and each record appears in a row

• The DataGrid control’s DataBind method is used to bind the control to the dataset


Including a DataGrid Control on a Web Form (continued)

Figure 12-72: Web form for the Fairview application


Including a DataGrid Control on a Web Form (continued)

• DataGrid control provides many properties to control the appearance of its output

• DataGrid control provides an Auto Format dialog box that allows selection from a list of predefined formats, or schemes, for displaying data


Summary

• To access a database from a Visual Basic .NET application, use the DataAdapter, Connection, and DataSet objects

• Use SQL SELECT to specify the fields and records to view, and to control the order in which the fields and records appear when displayed

• Use the Fill method to fill a dataset with data while an application is running


Summary (continued)

• To bind a DataSet object to a DataGrid control

– Set DataGrid control’s DataSource property to the name of the DataSet object

– Set DataMember property to the name of a table

• To bind a DataSet object to a list box

– Set the list box’s DataSource property to the name of the DataSet object

– Set its DisplayMember property to the name of the table and field


Summary (continued)

• To add a control to a Web form, use the tools on the Web Forms tab in the toolbox

• To validate user input on a Web page, use one or more Web validator tools

• To determine whether a postback has occurred, use the Web form’s IsPostBack property

• To bind a Web DataGrid control to a dataset, use the DataBind method

chapter 12: ado.net and asp.net programming with microsoft visual basic.net, second edition

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