Clearly Visual Basic: Programming with Visual Basic 2008 Chapter 25 I’m Suffering from Information...

Clearly Visual Basic: Programming with Visual Basic 2008

Chapter 25 I’m Suffering from Information

Overload


Objectives

• Define the terms used when talking about databases

• Connect an application to a Microsoft Access database

• Bind table and field objects to controls

• Customize a DataGridView control

• Handle exceptions using the Try…Catch statement

• Position the record pointer in a dataset

2


Keeping Good Records

• Computer database – Electronic file that contains an organized collection of

related information

• Relational database– Stores information in tables composed of columns

and rows

• Field – Single item of information about a person, place, or

thing

3


Keeping Good Records (continued)

• Record – Group of related fields that contain all the necessary

data about a specific person, place, or thing

• Table– Group of related records

• Primary key– Field that uniquely identifies each record in a table

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Clearly Visual Basic: Programming with Visual Basic 2008 5


Keeping Good Records (continued)

• Figure 25-2– CD_Number field

• Primary key in parent table

– CD_Number field in child table • Used solely to link song title and track information to

the appropriate CD in parent table

– Child table• CD_Number field is called the foreign key

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Connecting … Connecting

• Figure 25-3– Emp_Number field is the primary key– Status field contains the employment status– Code field identifies the employee’s department

• Data Source Configuration Wizard– Easiest way to connect an application to a database

8


Let the Computer Do It

• Binding– Connecting an object to a control

• Bound controls– The connected controls

• DataGridView control – Displays data in row and columnar format, similar to

a spreadsheet– One of the most popular controls for displaying table

data

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Let the Computer Do It (continued)

• While an application is running, you can use the BindingNavigator control to:– Move from one record to the next in the dataset– Add or delete a record and save any changes made

to the dataset

• Component tray – Stores objects that do not appear in the user

interface while an application is running

• TableAdapter object in the component tray – Connects the database to the DataSet object

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Let the Computer Do It (continued)

• TableAdapterManager object – Used to save changes made to the database

• BindingSource object – Provides the connection between the DataSet and

the bound controls on the Form• TblEmployBindingSource in Figure 25-7

– Connects EmployeesDataSet to two bound controls• DataGridView control and BindingNavigator control

• Figure 25-8– Shows relationship between database, DataSet, and

Form

13


The Copy to Output Directory Property

• When the Data Source Configuration Wizard connects an application to a database:– It adds the database file to the application’s project

folder

• Method of saving changes to a local database file – Is determined by the file’s Copy to Output

Directory property

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How Does Visual Basic Do It?

• When a table or field object is dragged to the form: – Computer adds the appropriate controls and objects

to the application

• A form’s Load event – Occurs when the application is started and the form

is displayed for the first time

• Load event procedure– Code to fill a dataset with data belongs here

17


Thank You for Catching My Errors

• Exceptions– Handled in Visual Basic by displaying an error

message and then abruptly terminating the application

• Try…Catch statement– Used to take control of the exception handling in

your code

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I’ll Use My Own Controls, Thank You

• To bind an object in a dataset to an existing control on the form:– Drag the object from the Data Sources window to the

control

• BindingSource object – Uses an invisible record pointer to keep track of the

current record in the dataset

• Position property– Stores the position of the record pointer

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Summary

• Relational database can contain one or more tables• Data in a relational database

– Can be displayed in any order

• Most tables contain a primary key that uniquely identifies each record

• To access the data stored in a database:– First connect the application to the database

• You display the information contained in a dataset by: – Binding one or more of the dataset objects to one or

more controls in the application’s interface

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Summary (continued)

• TableAdapter object – Connects a database to a DataSet object

• DataGridView control – Displays data in a row and columnar format

• Try…Catch statement – Used to handle exceptions that occur while an

application is running

• BindingSource object – Uses an invisible record pointer to keep track of the

current record in a dataset

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Clearly Visual Basic: Programming with Visual Basic 2008 Chapter 25 I’m Suffering from Information...

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