Download Chapter 12

Chapter 12: Using ADO.NET 2.0
Programming with Microsoft Visual Basic
2005, Third Edition
Databases
Lesson A Objectives
• Define the terms used when talking about
databases
• Connect an application to a database
• Bind table and field objects to controls
• Explain the purpose of the DataSet, BindingSource,
TableAdapter, and BindingNavigator objects
Programming with Microsoft Visual Basic 2005, Third Edition
2
Databases
Lesson A Objectives (continued)
• Access the records in a dataset
• Move the record pointer
Programming with Microsoft Visual Basic 2005, Third Edition
3
Previewing the Trivia Game
Application
•
•
•
•
Go to Run command on Windows Start menu
Browse to the VB2005\Chap12 folder
Open the Trivia Game.exe file
Trivia Game application user interface appears
Programming with Microsoft Visual Basic 2005, Third Edition
4
Previewing the Trivia Game
Application (continued)
Figure 12-1: Trivia Game application
Programming with Microsoft Visual Basic 2005, Third Edition
5
Database Terminology
• Database: organized collection of related information
• Relational database
– Database that stores information in tables
– Each column in a table represents a field
– Each row in a table represents a record
• Primary key: field uniquely identifying a record
• A two-table database has parent and child tables
• Foreign key: links child record to parent record
Programming with Microsoft Visual Basic 2005, Third Edition
6
Database Terminology (continued)
Figure 12-2: Example of a one-table relational database
Programming with Microsoft Visual Basic 2005, Third Edition
7
Database Terminology (continued)
Figure 12-3: Example of a two-table relational database
Programming with Microsoft Visual Basic 2005, Third Edition
8
ADO.NET 2.0
• ADO (ActiveX Data Objects).Net 2.0 technology
– Connects an application to a database
– Allows application to read from and write to database
– Connection is closed after dataset is copied or saved
• Dataset: copy of records application wants to access
• Opening Employees.mdf in IDE window
– Connect the database to an application
– Right-click table’s name in Server Explorer window
– Click Show Table Data
Programming with Microsoft Visual Basic 2005, Third Edition
9
ADO.NET (continued)
Figure 12-4: Data contained in the tblEmploy table
Programming with Microsoft Visual Basic 2005, Third Edition
10
Connecting an Application to a
Database
• Create a database connection to access data
• Data Source Configuration Wizard
– Helps you connect an application to a database
Programming with Microsoft Visual Basic 2005, Third Edition
11
Connecting an Application to a
Database (continued)
Figure 12-5: Procedure for connecting an application to a database
Programming with Microsoft Visual Basic 2005, Third Edition
12
Connecting an Application to a
Database (continued)
Figure 12-12: EmployeesDataSet added to the Data Sources window
Programming with Microsoft Visual Basic 2005, Third Edition
13
Previewing the Data Contained in a
Dataset
• Right-click the Data Sources window
• Click Preview Data to open Preview Data dialog
box
• Select the object to preview, then click Preview
• After previewing the data, click the Close button
Programming with Microsoft Visual Basic 2005, Third Edition
14
Previewing the Data Contained in a
Dataset (continued)
Figure 12-14: Data displayed in the Preview Data dialog box
Programming with Microsoft Visual Basic 2005, Third Edition
15
Binding the Objects in a Dataset
•
•
•
•
Bind dataset objects before viewing contents
Binding: connecting a dataset object to a control
Bound controls: the connected controls
Types of controls used to bind dataset objects
– Computer-created control
– Existing control
Programming with Microsoft Visual Basic 2005, Third Edition
16
Binding the Objects in a Dataset
(continued)
Figure 12-15: Ways to bind the objects in a dataset
Programming with Microsoft Visual Basic 2005, Third Edition
17
Having the Computer Create a
Bound Control
• Impact of dragging dataset object to form
– Computer creates control (indicated by icon)
– Dataset object is automatically bound to control
• Example
– Drag tblEmployee table object to form
– DataGridView control displays tabular data
– Rows represent records, columns represent fields
• Use list arrow to change control linked to object
Programming with Microsoft Visual Basic 2005, Third Edition
18
Having the Computer Create a
Bound Control (continued)
Figure 12-17: Result of clicking the tblEmploy table
object’s list arrow
Programming with Microsoft Visual Basic 2005, Third Edition
19
Having the Computer Create a
Bound Control (continued)
Figure 12-20: Illustration of the relationships among the
database, the objects in the component tray, and the
controls on the form
Programming with Microsoft Visual Basic 2005, Third Edition
20
The Copy to Output Directory
Property
• Determines the way a file is handled in application
• Copy always
–
–
–
–
Default setting of Copy to Output Directory property
Database file copied to project’s bin\Debug folder
Result: .mdf file appears in two different folders
Changes to file in bin\Debug folder are overwritten
• Copy if newer
– Set this property to preserve run-time changes
– Copies over file in bin\Debug only if file is not current
Programming with Microsoft Visual Basic 2005, Third Edition
21
Binding to an Existing Control
• Method 1
– Drag object from Data Sources window to control
• Method 2
– Click the control
– Set one or more properties in the Properties window
• Properties to set depends on control being bound
– DataGrid: set DataSource and DataMember
– ListBox: set DataSource and DisplayMember
Programming with Microsoft Visual Basic 2005, Third Edition
22
Binding to an Existing Control
(continued)
Figure 12-23: Result of dragging the field objects to the existing
label controls
Programming with Microsoft Visual Basic 2005, Third Edition
23
Accessing the Records in a Dataset
• BindingSource object’s Position property
– Stores an invisible record pointer
– Positions are integer values  = 0
• Syntax: bindingSourceName.Position
• Example
– Me.TblEmployBindingSource.Position = 4
– Moves record pointer to fifth record in the dataset
• BindingSource object’s Move methods
– Also used to move the record pointer in a dataset
Programming with Microsoft Visual Basic 2005, Third Edition
24
Accessing the Records in a Dataset
(continued)
Figure 12-25: Syntax and examples of the BindingSource
object’s Move methods
Programming with Microsoft Visual Basic 2005, Third Edition
25
Summary – Lesson A
• A relational database stores information in tables
• Tables comprise rows (records) and columns (fields)
• Two-table database comprises parent and child
tables
• Two types of id fields: primary key and foreign key
• Relational database is stored as a file on disk
Programming with Microsoft Visual Basic 2005, Third Edition
26
Summary – Lesson A (continued)
• ADO.NET 2.0 connects application to database
• Dataset: copies of records from database stored in
main memory
• To view dataset objects, they must be bound to a
control
• Use BindingSource object’s Position property or its
Move methods to move the record pointer
Programming with Microsoft Visual Basic 2005, Third Edition
27
Creating Queries
Lesson B Objectives
• Write SQL SELECT statements
• Create a query using the Query Configuration
Wizard
• Associate a ToolStrip control with a query
Programming with Microsoft Visual Basic 2005, Third Edition
28
The DataSet Designer
• Browse to VB2005\Chap12 folder
• Copy Morgan Industries Solution-DataGrid folder
• Rename copy as follows:
– Morgan Industries Solution-DataGrid-Query
• Open new file in Visual Studio 2005
Programming with Microsoft Visual Basic 2005, Third Edition
29
The DataSet Designer (continued)
Figure 12-26: Data displayed in the TblEmployDataGridView control
Programming with Microsoft Visual Basic 2005, Third Edition
30
The DataSet Designer (continued)
• DataSet Designer controls the display of data
– Shows name of table and field objects for dataset
– Also shows the name of TableAdapter object
•
•
•
•
TableAdapter object: queries underlying database
Query: specifies fields and records to retrieve
DataSet Designer puts .xsd file in Solution Explorer
.xsd extension indicates XML schema definition file
– XML (extensible markup language)
– .xsd file type defines tables and fields for a dataset
Programming with Microsoft Visual Basic 2005, Third Edition
31
The DataSet Designer (continued)
Figure 12-27: Three ways to open the DataSet Designer
Programming with Microsoft Visual Basic 2005, Third Edition
32
The Dataset Designer (continued)
Figure 12-28: DataSet Designer
Programming with Microsoft Visual Basic 2005, Third Edition
33
Structured Query Language
• Structured Query Language (SQL)
– Access/manipulate data stored in databases
– Organized as a set of commands
• Database tasks performed with SQL commands
– Storing, retrieving, updating, deleting, and sorting
• SELECT statement
– Most commonly used command in SQL
– Specifies the fields and records you want to view
– Refine query with WHERE and/or ORDER BY clause
Programming with Microsoft Visual Basic 2005, Third Edition
34
Structured Query Language
(continued)
Figure 12-30: Syntax and examples of the SELECT statement
(continued)
Programming with Microsoft Visual Basic 2005, Third Edition
35
Structured Query Language
(continued)
Figure 12-30: Syntax and examples of the SELECT statement
Programming with Microsoft Visual Basic 2005, Third Edition
36
Creating a New Query
• Use TableAdapter Query Configuration Wizard
Programming with Microsoft Visual Basic 2005, Third Edition
37
Creating a New Query (continued)
Figure 12-31: Procedure for creating a query using the
TableAdapter Query Configuration Wizard
Programming with Microsoft Visual Basic 2005, Third Edition
38
Creating a New Query (continued)
Figure 12-38: SELECT statement containing the WHERE and
ORDER BY clauses
Programming with Microsoft Visual Basic 2005, Third Edition
39
Allowing the User to Run a Query
• ToolStrip control
– Allows a user to run a query at runtime
• How to add query feature
–
–
–
–
–
–
Right-click the name of the TableAdapter object
Click Add Query to open Search Criteria Builder dialog
Select the Existing query name radio button
Click the down arrow in list box next to radio button
Click the name of the query in the list
Click OK button to close Search Criteria Builder dialog
Programming with Microsoft Visual Basic 2005, Third Edition
40
Allowing the User to Run a Query
(continued)
Figure 12-44: ToolStrip control and object added to the application
Programming with Microsoft Visual Basic 2005, Third Edition
41
Summary – Lesson B
• DataSet Designer: used to control the display of
fields and records from a database
• TableAdapter object: connects dataset to underlying
database using queries
• Query: specifies fields and records to retrieve from a
database
• Structured Query Language (SQL): set of commands
used to access and manipulate data in a database
• Select statement: specifies fields/records to view
Programming with Microsoft Visual Basic 2005, Third Edition
42
The Trivia Game Application
Lesson C Objectives
• Connect a SQL Server database to an
application
• Bind field objects to controls in an interface
• Position the record pointer in a dataset
• Determine the number of records in a dataset
Programming with Microsoft Visual Basic 2005, Third Edition
43
Coding the Trivia Game Application
• Review requirements for Trivia Game application
–
–
–
–
Display questions along with answers
Allow user to select from set of answers
Track number of incorrect answers
Display information at the end of the game
• Location of partial solution
– VB2005\Chap12\Trivia Game Solution folder
• First set of tasks
– Connect application to Trivia.mdf, define dataset
Programming with Microsoft Visual Basic 2005, Third Edition
44
Coding the Trivia Game Application
(continued)
Figure 12-47: Completed Add Connection dialog box
Programming with Microsoft Visual Basic 2005, Third Edition
45
Coding the Trivia Game Application
(continued)
Figure 12-49: TriviaDataSet added to the Data Sources window
Programming with Microsoft Visual Basic 2005, Third Edition
46
Coding the Trivia Game Application
(continued)
• Tasks following definition of the dataset
– Preview data that can be displayed
– Bind field objects to text boxes
• Three event procedures to code
– xExitButton’s Click event procedure
– MainForm’s Load event procedure
– xSubmitButton’s Click event procedure
• Test the application after all code is added
Programming with Microsoft Visual Basic 2005, Third Edition
47
Coding the Trivia Game Application
(continued)
Figure 12-51: Question field object being
dragged to the xQuestionTextBox
Programming with Microsoft Visual Basic 2005, Third Edition
48
Coding the Trivia Game Application
(continued)
Figure 12-55: Pseudocode for the xSubmitButton’s
Click event procedure
Programming with Microsoft Visual Basic 2005, Third Edition
49
Summary – Lesson C
• First step for accessing a database: connect the
application to a database
• Following connection to database, specify field
objects that will form a dataset
• Dataset objects can be bound to interface controls
• Methods of BindingSource objects enable you to
move through records
Programming with Microsoft Visual Basic 2005, Third Edition
50