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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