using ado.net chapter microsoft visual basic.net: reloaded 1

Using ADO.NET

Chapter Microsoft Visual Basic .NET: Reloaded

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2Microsoft Visual Basic .NET: Reloaded

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


Objectives (continued)

• Create a dataset

• Display a dataset in various controls in an interface

• Position the record pointer in a dataset


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


Database Terminology (continued)


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


ADO.NET (continued)


Creating and Configuring a DataAdapter Object


Creating and Configuring a DataAdapter Object (continued)


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


HOW TO…


HOW TO… (continued)


Using the Query Builder to Enter a SELECT Statement


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


Creating a DataSet


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


Using the Fill Method

• Method of the DataAdapter object• Fills a dataset with data while the application

is running


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”


HOW TO…


Binding the Dataset Object to a DataGrid Control (continued)


Reconfiguring the DataAdapter Object


Reconfiguring the DataAdapter Object (continued)


Binding the Dataset Object to a Label Control or Text box


Binding the Dataset Object to a Label Control or Text box (continued)


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


Programming Example – Cartwright Industries Application (continued)

• Items.mdb database opened in Microsoft Access. Database contains one table tblItems


TOE Chart


User Interface


Objects, Properties, and Settings


Tab Order


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


Code


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


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


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


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

using ado.net chapter microsoft visual basic.net: reloaded 1

Documents

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