Download 0619215658_236962

Chapter
Microsoft Visual Basic .NET: Reloaded
Using ADO.NET
1
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
• Write SQL SELECT statements
Microsoft Visual Basic .NET: Reloaded
2
Objectives (continued)
• Create a dataset
• Display a dataset in various controls in an
interface
• Position the record pointer in a dataset
Microsoft Visual Basic .NET: Reloaded
3
Database Terminology
• Database
• Organized collection of related information
stored in a file on a disk
• Relational database stores information in
tables composed of columns and rows
• Table is a group of related records
• Each row represents a record
• Each column represents a row
• Primary key is a field that uniquely identities a
record in a table
• Foreign key is a field in one table used as the
primary key in another table
• Tables are related by a common field or fields
Microsoft Visual Basic .NET: Reloaded
4
Database Terminology (continued)
Microsoft Visual Basic .NET: Reloaded
5
Database Terminology (continued)
Microsoft Visual Basic .NET: Reloaded
6
ADO.NET
• A Connection object is used to establish a
temporary connection to a database
• Requests for information are then submitted
using a DataAdapter object
• The DataAdapter uses a provider which
translates the request into a language the
database understands
• A DataSet stores a copy of the records and
fields requested in a internal memory location
Microsoft Visual Basic .NET: Reloaded
7
ADO.NET (continued)
Microsoft Visual Basic .NET: Reloaded
8
ADO.NET (continued)
Microsoft Visual Basic .NET: Reloaded
9
Creating and Configuring a
DataAdapter Object
Microsoft Visual Basic .NET: Reloaded
10
Creating and Configuring a
DataAdapter Object (continued)
Microsoft Visual Basic .NET: Reloaded
11
Creating and Configuring a
DataAdapter Object (continued)
Microsoft Visual Basic .NET: Reloaded
12
Creating and Configuring a
DataAdapter Object (continued)
Microsoft Visual Basic .NET: Reloaded
13
Creating and Configuring a
DataAdapter Object (continued)
Microsoft Visual Basic .NET: Reloaded
14
Creating and Configuring a
DataAdapter Object (continued)
Microsoft Visual Basic .NET: Reloaded
15
SQL
• Structured Query Language (SQL)
• A set of commands that allows you to access
and manipulate the data stored in many
database management systems on computers
of all sizes
• SELECT statement allow you to specify which
fields and records you want to view
• WHERE clause limits records to be selected
• ORDER BY clause sorts record display order
Microsoft Visual Basic .NET: Reloaded
16
HOW TO…
Microsoft Visual Basic .NET: Reloaded
17
HOW TO… (continued)
Microsoft Visual Basic .NET: Reloaded
18
Using the Query Builder to Enter a
SELECT Statement
Microsoft Visual Basic .NET: Reloaded
19
Using the Query Builder to Enter a
SELECT Statement (continued)
Microsoft Visual Basic .NET: Reloaded
20
Using the Query Builder to Enter a
SELECT Statement (continued)
Microsoft Visual Basic .NET: Reloaded
21
Using the Query Builder to Enter a
SELECT Statement (continued)
Microsoft Visual Basic .NET: Reloaded
22
Using the Query Builder to Enter a
SELECT Statement (continued)
Microsoft Visual Basic .NET: Reloaded
23
Using the Query Builder to Enter a
SELECT Statement (continued)
Microsoft Visual Basic .NET: Reloaded
24
Using the Query Builder to Enter a
SELECT Statement (continued)
Microsoft Visual Basic .NET: Reloaded
25
Creating a DataSet
Microsoft Visual Basic .NET: Reloaded
26
Creating a DataSet (continued)
Microsoft Visual Basic .NET: Reloaded
27
Creating a DataSet (continued)
• XML (Extensible Markup Language)
• XML schema definition file defines the tables
and fields that make up the data set
• Schema file is automatically generated by
VB.NET
• Contents of file may be viewed in IDE
• Contents of dataset can be preview by right
clicking the DataAdapter object in the
component tray and clicking Preview Data
Microsoft Visual Basic .NET: Reloaded
28
Creating a DataSet (continued)
Microsoft Visual Basic .NET: Reloaded
29
Using the Fill Method
• Method of the DataAdapter object
• Fills a dataset with data while the application
is running
Microsoft Visual Basic .NET: Reloaded
30
Binding the Dataset Object to a
DataGrid Control
• Connecting a DataSet object to a control is
called “binding”
• Connected controls are referred to as “bound
controls”
Microsoft Visual Basic .NET: Reloaded
31
HOW TO…
Microsoft Visual Basic .NET: Reloaded
32
Binding the Dataset Object to a
DataGrid Control (continued)
Microsoft Visual Basic .NET: Reloaded
33
Reconfiguring the DataAdapter Object
Microsoft Visual Basic .NET: Reloaded
34
Reconfiguring the DataAdapter Object
(continued)
Microsoft Visual Basic .NET: Reloaded
35
Reconfiguring the DataAdapter Object
(continued)
Microsoft Visual Basic .NET: Reloaded
36
Binding the Dataset Object to a Label
Control or Text box
Microsoft Visual Basic .NET: Reloaded
37
Binding the Dataset Object to a Label
Control or Text box (continued)
Microsoft Visual Basic .NET: Reloaded
38
Binding the Dataset Object to a Label
Control or Text box (continued)
Microsoft Visual Basic .NET: Reloaded
39
Binding the Dataset Object to a Label
Control or Text box (continued)
Microsoft Visual Basic .NET: Reloaded
40
Programming Example – 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
• The database is contained in the
VbDotNet\Chap12\Databases folder.
• Mr. Simons wants an application that the
sales clerks can use to enter an item number
and then display the item’s price
Microsoft Visual Basic .NET: Reloaded
41
Programming Example – Cartwright
Industries Application (continued)
• Items.mdb database opened in Microsoft
Access. Database contains one table
tblItems
Microsoft Visual Basic .NET: Reloaded
42
TOE Chart
Microsoft Visual Basic .NET: Reloaded
43
User Interface
Microsoft Visual Basic .NET: Reloaded
44
Objects, Properties, and Settings
Microsoft Visual Basic .NET: Reloaded
45
Tab Order
Microsoft Visual Basic .NET: Reloaded
46
Pseudocode
btnExit Click event procedure
1. close application
frmCartwright Load event procedure
1. fill the dataset with the item numbers and
prices from the Items.mdb database
Microsoft Visual Basic .NET: Reloaded
47
Code
Microsoft Visual Basic .NET: Reloaded
48
Summary
• Databases created by Microsoft Access are
relational databases:
• Can contain one or more tables
• Most tables contain a primary key that
uniquely identifies each record
• Data in relational database can be displayed
in any order, and you can control the amount
of information you want to view
• Visual Basic .NET uses a technology called
ADO.NET to access the data stored in a
database
Microsoft Visual Basic .NET: Reloaded
49
Summary (continued)
• Connection between a database and an
application that uses ADO.NET is only
temporary
• To access data stored in a database, first
create and configure a DataAdapter object,
which is the link between the application and
the Connection object
• Use an OleDbDataAdapter object and an
OleDbConnection object in applications that
access Microsoft Access databases
Microsoft Visual Basic .NET: Reloaded
50
Summary (continued)
• DataAdapter, Connection, and DataSet
objects are stored in component tray
• Use SQL SELECT statement to specify fields
and records for a dataset
• Query Builder provides a convenient way to
create a SELECT statement
• Dataset contains data you want to access
from the database
• Data specified in SELECT statement
associated with DataAdapter object
Microsoft Visual Basic .NET: Reloaded
51
Summary (continued)
• Use DataAdapter object’s Fill method to fill a
dataset with data while an application is
running
• Users view data stored in a dataset through
controls that are bound to DataSet object
• Use DataGrid control to display records
contained in a dataset
• When you change the SELECT statement
associated with a DataAdapter object, you
must regenerate the dataset
Microsoft Visual Basic .NET: Reloaded
52