1. Chapter 14: Advanced Topics: DBMS, SQL, and ASP.NET
Visual Basic .NET Programming:
From Problem Analysis to Program Design

2. Visual Basic .NET Programming: From Problem Analysis to Program Design
Objectives
Explore the relational database model
Construct database queries using SQL
Write VB .NET programs that interact with a relational database
Explore ASP.NET
Visual Basic .NET Programming: From Problem Analysis to Program Design

3. Exploring the Relational Database Model
Real-world applications require data persistence
VB .NET provides several mechanisms
Sequential files
Relational database
Visual Basic .NET Programming: From Problem Analysis to Program Design

4. Understanding Tables, Rows, Columns, and Primary and Foreign Keys
Organize data
Relational database consists of many different tables
Related to each other in some way
Consist of
Rows
Columns
Visual Basic .NET Programming: From Problem Analysis to Program Design

5. Visual Basic .NET Programming: From Problem Analysis to Program Design
Understanding Tables, Rows, Columns, and Primary and Foreign Keys (continued)
Rows
Records
Instances
Columns
Attributes
Fields
Visual Basic .NET Programming: From Problem Analysis to Program Design

6. Visual Basic .NET Programming: From Problem Analysis to Program Design
Understanding Tables, Rows, Columns, and Primary and Foreign Keys (continued)
Primary key
Field that uniquely identifies each record
Good database design calls for primary key whose
Value is not likely to change over time
Value is not null for any instance
Can add unique identifying attribute to table
Visual Basic .NET Programming: From Problem Analysis to Program Design

7. Visual Basic .NET Programming: From Problem Analysis to Program Design
Understanding Tables, Rows, Columns, and Primary and Foreign Keys (continued)
Foreign key
Links information in one table to information in another table
Must be primary key in other table
Visual Basic .NET Programming: From Problem Analysis to Program Design

8. Visual Basic .NET Programming: From Problem Analysis to Program Design

9. Mapping PD Attributes to Database Tables
Many different choices for organizing attributes into relational tables
Attributes can be mapped to more than one table
Can add fields that were not originally contained in PD class
Seldom single choice
Weigh benefits and drawbacks of several possible designs
Choose design that best fits needs of application
Visual Basic .NET Programming: From Problem Analysis to Program Design

10. Visual Basic .NET Programming: From Problem Analysis to Program Design

11. Visual Basic .NET Programming: From Problem Analysis to Program Design

12. Visual Basic .NET Programming: From Problem Analysis to Program Design

13. Constructing Queries Using SQL
Query
Request for information.
Usually specifies one or more conditions that extracted information must meet
Can be written in Structured Query Language
SQL
Visual Basic .NET Programming: From Problem Analysis to Program Design

14. Constructing Queries Using SQL (continued)
Enables you to perform other common database operation
Insert
Update
Delete
Visual Basic .NET Programming: From Problem Analysis to Program Design

15. Extracting Records from a Database
SELECT statement.
Format:
SELECT attribute1, attribute2, ... , attributeN
FROM table
WHERE condition
Each attribute specifies name of column
Table specifies name of table
Condition specifies criteria for selecting records from table
Visual Basic .NET Programming: From Problem Analysis to Program Design

16. Extracting Records from a Database (continued)
SELECT statement
Example:
SELECT FirstName, LastName FROM Customer WHERE State = ‘GA’
Can use keywords AND and OR
To specify compound conditions
Extract attributes from multiple tables
Visual Basic .NET Programming: From Problem Analysis to Program Design

17. Inserting Records into a Database
INSERT statement
Formats:
INSERT INTO table VALUES (value1, value2, ... , valueN)
INSERT INTO table (attribute1, attribute2, ... , attributeN) VALUES (value1, value2, ... , valueN)
First format
Must know order of fields in underlying table
Visual Basic .NET Programming: From Problem Analysis to Program Design

18. Inserting Records into a Database (continued)
INSERT statement
Example:
INSERT INTO Customer VALUES ('51954', 'John', 'Doe', 'Miami', 'FL', ' ')
Visual Basic .NET Programming: From Problem Analysis to Program Design

19. Updating Records in a Database
UPDATE statement
Format:
UPDATE table
SET attribute1=value1, attribute2=value2, ..., attributeN=valueN
WHERE condition
SET clause
Assign values to each attribute to be modified
Visual Basic .NET Programming: From Problem Analysis to Program Design

20. Updating Records in a Database (continued)
UPDATE statement (continued)
WHERE clause
Specifies to which record UPDATE command applies
Example:
UPDATE Customer SET State = 'Georgia' WHERE State = 'GA'
Visual Basic .NET Programming: From Problem Analysis to Program Design

21. Deleting Records from a Database
DELETE statement
Format:
DELETE FROM table WHERE condition
WHERE clause
Specifies conditions that determine record to delete
Example:
DELETE FROM Customer WHERE State = 'Georgia'
Visual Basic .NET Programming: From Problem Analysis to Program Design

22. Writing VB .NET Programs that Interact with a Relational Database
VB .NET Framework provides support for several database management systems including:
Oracle
Microsoft Access
Microsoft SQLServer
Visual Basic .NET Programming: From Problem Analysis to Program Design

23. Visual Basic .NET Programming: From Problem Analysis to Program Design
Writing VB .NET Programs that Interact with a Relational Database (continued)
Data providers
Used to
Connect to database
Execute commands,
Retrieve results
Namespaces:
System.Data
System.Data.OleDb
Visual Basic .NET Programming: From Problem Analysis to Program Design

24. Visual Basic .NET Programming: From Problem Analysis to Program Design

25. Visual Basic .NET Programming: From Problem Analysis to Program Design

26. Visual Basic .NET Programming: From Problem Analysis to Program Design

27. Understanding the Examples in this Section
Build on Programming Example presented at end of Chapter 13
Integrated system
Adding students and professors to database
Producing lists of students and professors.
Extends functionality to allow updating/deleting
Visual Basic .NET Programming: From Problem Analysis to Program Design

28. Visual Basic .NET Programming: From Problem Analysis to Program Design

29. Understanding the Examples in this Section (continued)
Three-tier design
PD and GUI classes are unaware of how DA class implements data persistence
DA class handles all interaction with database and carries out tasks of:
Inserting
Updating
Deleting
Extracting information
Visual Basic .NET Programming: From Problem Analysis to Program Design

30. Understanding the Examples in this Section (continued)
Three-tier design
GUI classes that capture and display information simply invoke DA methods
Visual Basic .NET Programming: From Problem Analysis to Program Design

31. Making the StudentDA Class Work with an Access Database
Import namespaces that provide functionality to interact with Microsoft Access database
Initialize method
Creates and opens connection to database
Attempt to open connection is enclosed within Try- Catch block
Visual Basic .NET Programming: From Problem Analysis to Program Design

32. Making the StudentDA Class Work with an Access Database (continued)
GetAll method
Issues SELECT command to retrieve all records from database
General approach for executing SELECT command:
Create data set instance
Create data adapter instance
Visual Basic .NET Programming: From Problem Analysis to Program Design

33. Making the StudentDA Class Work with an Access Database (continued)
General approach for executing SELECT command (continued):
Define String variable containing SELECT statement
Use SelectCommand property of data adapter to create command instance and execute command against database
Invoke Fill method of data adapter class to populate data set
Visual Basic .NET Programming: From Problem Analysis to Program Design

34. Making the StudentDA Class Work with an Access Database (continued)
Find method
Nearly identical to GetAll method
SELECT statement issued within Find method returns at most one record
AddNew method
Insert new record into database
Visual Basic .NET Programming: From Problem Analysis to Program Design

35. Making the StudentDA Class Work with an Access Database (continued)
To create and execute INSERT command in VB.NET:
Create data adapter instance
Create instance of OleDbCommand class
Assign instance to data adapter’s InsertCommand
Invoke ExecuteNonQuery method of OleDbCommand class
Visual Basic .NET Programming: From Problem Analysis to Program Design

36. Making the StudentDA Class Work with an Access Database (continued)
Update method
Similar to AddNew method.
Defines SQL statement to update database
Delete method
Defines SQL DELETE statement
Deletes record from database
Terminate method
Closes database connection
Visual Basic .NET Programming: From Problem Analysis to Program Design

37. Making the StudentDA Class Work with an Access Database (continued)
Exception classes:
NotFoundException
DuplicateException
Visual Basic .NET Programming: From Problem Analysis to Program Design

38. Recognizing the Benefits of the Three-Tier Design
Very little change required to PD and GUI classes
To make them work with new StudentDA class
Visual Basic .NET Programming: From Problem Analysis to Program Design

39. Visual Basic .NET Programming: From Problem Analysis to Program Design
Programming Example: Updating and Deleting Records in a Relational Database
Demonstrates how to update and delete records from relational database in three-tier design
Using methods of StudentDA class
Benefit of three-tier design
Add new GUIs without having to make changes in PD and DA tiers
Visual Basic .NET Programming: From Problem Analysis to Program Design

40. Visual Basic .NET Programming: From Problem Analysis to Program Design

41. Visual Basic .NET Programming: From Problem Analysis to Program Design
Introducing ASP.NET
ASP.NET
Used to write interactive web pages
Visual Basic .NET Programming: From Problem Analysis to Program Design

42. Visual Basic .NET Programming: From Problem Analysis to Program Design
Reviewing Web Basics
Hypertext Markup Language (HTML)
Employed by web pages
Enables browsers to display Web pages on variety of computing platforms
Descriptive language
Uniform Resource Locator (URL)
ASP.NET
Can contain HTML and related files containing code to provide interactivity
Visual Basic .NET Programming: From Problem Analysis to Program Design

43. Reviewing Web Basics (continued)
Web pages
Actual files containing HTML code
Have extension of .htm or .html
Contains tags that define format of Web page
Can be created using any text editor
Such as Notepad
Visual Basic .NET Programming: From Problem Analysis to Program Design

44. Visual Basic .NET Programming: From Problem Analysis to Program Design

45. Creating ASP.NET Projects
NET Framework provides tools to develop both
Windows applications
Web applications
ASP.NET separates procedural code from Web form (HTML) code:
Web form file has suffix of .aspx,
Code file has suffix .vb
Called code-behind file
Visual Basic .NET Programming: From Problem Analysis to Program Design

46. Creating ASP.NET Projects (continued)
In new projects dialog box in Visual Studio .NET
Choose ASP.NET Web Application template
Use Toolbox to add form components
Display Web Forms or HTML sections
Visual Basic .NET Programming: From Problem Analysis to Program Design

47. Visual Basic .NET Programming: From Problem Analysis to Program Design

48. Visual Basic .NET Programming: From Problem Analysis to Program Design

49. Creating ASP.NET Projects (continued)
Validation controls
Facilitate adding data validation
Appear in Toolbox
Can be placed on Web page just as any other controls
Properties can be accessed in Properties window
Visual Basic .NET Programming: From Problem Analysis to Program Design

50. Visual Basic .NET Programming: From Problem Analysis to Program Design

51. Programming Example: Electricity Billing
Deploys Electricity Billing Programming Example at end of Chapter 10
As ASP.NET Web-based application
GUI
Inputs and validates
Customer Number
Previous, and Current Meter Readings
Visual Basic .NET Programming: From Problem Analysis to Program Design

52. Programming Example: Electricity Billing (continued)
Data validation:
Customer Number is required
Previous Reading is required
Must be in range 0–99999
Current Reading is required
Must be greater than or equal to Previous Reading
Visual Basic .NET Programming: From Problem Analysis to Program Design

53. Visual Basic .NET Programming: From Problem Analysis to Program Design
Summary
Applications require data to be persistent
Use relational databases
Relational database
Enables you to organize data into tables
Primary key
Field that uniquely identifies each record in table
Query
Request for information
Visual Basic .NET Programming: From Problem Analysis to Program Design

54. Visual Basic .NET Programming: From Problem Analysis to Program Design
Summary (continued)
Structured Query Language (SQL)
Allows you to specify queries
Three-tier design
PD and GUI classes are unaware of how data DA class implements data persistence
Web development using ASP.NET is similar to developing GUI applications for Windows
ASP.NET separates procedural code from Web form (HTML) code
Visual Basic .NET Programming: From Problem Analysis to Program Design