2002 prentice hall. all rights reserved. 1 chapter 19 – databases, sql, and ado.net outline:...

2002 Prentice Hall. All rights reserved.

1

Chapter 19 – Databases, SQL, and ADO.NET

Outline: 只上 19.1, 19.2, 19.3, 19.5, 19.619.1 Introduction19.2 Relational Database Model19.3 Relational Database Overview: The Books Database19.4 Structured Query Language (SQL)

19.4.1 Basic SELECT Query19.4.2 WHERE Clause19.4.3 ORDER BY Clause19.4.4 Merging Data from Multiple Tables: INNER

JOIN19.4.5 Joining Data from Tables Authors,

AuthorISBN, Titles and Publishers19.4.6 INSERT Statement19.4.7 UPDATE Statement19.4.8 DELETE Statement

19.5 ADO.NET Object Model


2

Outline19.6 Programming with ADO.NET: Extracting Information from a DBMS

19.6.1 Connecting to and Querying an Access Data Source

19.6.2 Querying the Books Database19.7 Programming with ADO.NET: Modifying a DBMS19.8 Reading and Writing XML Files


3

19.1 Introduction

• Database:– Integrated collection of data

– Database management system (DBMS)• Provides mechanisms for storing and organizing data in a way

that is consistent with database’s format

• Allows storage and access to database without knowledge of internal representation

– Relational Databases most popular• Use Structured Query Language to perform queries (search)

and manipulate data

• Programming languages need an interface to interact with relational databases


4

19.2 Relational Database Model

• Logical representation of data:– Relationships can be considered without concern for

physical structure of data

• Composed of tables– Rows called records

– Columns called fields

– Primary key: field that contains unique data• Each record can be identified by at least one distinct value

– New sets made from queries called result sets


5

19.2 Relational Database Model

Fig. 19.1 Relational database structure of an Employee table.

number name department salary location

23603 Jones 413 1100 New Jersey

24568 Kerwin 413 2000 New Jersey

34589 Larson 642 1800 Los Angeles

35761 Myers 611 1400 Orlando

47132 Neumann 413 9000 New Jersey

78321 Stephens 611 8500 Orlando

record/row

field/columnprimary key


6

19.3 Relational Database Overview: Books Database

• Rule of Entity Integrity: every record must have a unique value in its primary-key field

• Compound Primary key: when a record has a unique key based on a combination of two fields

• Foreign key:– Field for which every entry has a unique value in another

table and where the field in the other table is the primary key for that table

– Rule of Referential Integrity: every foreign-key field value must appear in another table’s primary-key field

– One to many relationship: A foreign key can appear many times in its own table, but only once as primary key in another table


7


Fig. 19.2 Result set formed by selecting Department and Location data from the Employee table.

department location

413 New Jersey

642 Los Angeles

611 Orlando


8


Field Description authorID Author’s ID number in the database. In the Books database, this integer field is

defined as an auto-incremented field. For each new record inserted in this table, the database automatically increments the authorID value to ensure that each record has a unique authorID. This field represents the table’s primary key.

firstName Author’s first name (a string).

lastName Author’s last name (a string).

Fig. 19.3 Authors table from Books.

Fig. 19.3 Authors table from Books.


9


authorID firstName lastName

1 Harvey Deitel

2 Paul Deitel

3 Tem Nieto

4 Kate Steinbuhler

5 Sean Santry

6 Ted Lin

7 Praveen Sadhu

8 David McPhie

9 Cheryl Yaeger

10 Marina Zlatkina

11 Ben Wiedermann

12 Jonathan Liperi

Fig. 19.4 Data from the Authors table of Books.

Fig. 19.4 Data from the Authors table of Books.


10


Field Description publisherID The publisher’s ID number in the database. This auto-incremented integer

is the table’s primary-key field.

publisherName The name of the publisher (a string).

Fig. 19.5 Publishers table from Books.

Fig. 19.5 Publishers table from Books.

publisherID publisherName

1 Prentice Hall

2 Prentice Hall PTG

Fig. 19.6 Data from the Publishers table of Books.

Fig. 19.6 Data from the Publishers table of Books.


11


Field Description authorID The author’s ID number, which allows the database to associate each

book with a specific author. The integer ID number in this field must also appear in the Authors table.

isbn The ISBN number for a book (a string).

Fig. 19.7 AuthorISBN table from Books.

Fig. 19.7 AuthorISBN table from Books.


12


authorID isbn authorID isbn

1 0130895725 2 0139163050

1 0132261197 2 013028419x

1 0130895717 2 0130161438

1 0135289106 2 0130856118

1 0139163050 2 0130125075

1 013028419x 2 0138993947

1 0130161438 2 0130852473

1 0130856118 2 0130829277

1 0130125075 2 0134569555

1 0138993947 2 0130829293

1 0130852473 2 0130284173

1 0130829277 2 0130284181

1 0134569555 2 0130895601

1 0130829293 3 013028419x

1 0130284173 3 0130161438

1 0130284181 3 0130856118

1 0130895601 3 0134569555

2 0130895725 3 0130829293

2 0132261197 3 0130284173

2 0130895717 3 0130284181

2 0135289106 4 0130895601

Fig. 19.8 Portion of data from table AuthorISBN in database Books.

Fig. 19.8 Portion of data from table AuthorISBN in database Books.


13


Field Description isbn ISBN number of the book (a string).

title Title of the book (a string).

editionNumber Edition number of the book (an integer).

copyright Copyright year of the book (a string).

publisherID Publisher’s ID number (an integer). This value must correspond to an ID number in the Publishers table.

imageFile Name of the file containing the book’s cover image (a string).

price Suggested retail price of the book (a real number). [Note: The prices shown in this book are for example purposes only.]

Fig. 19.9 Titles table from Books.

Fig. 19.9 Titles table from Books.


14


isbn title edition-Number

publish-erID

copy-right

imageFile

price

0130923613

Python How to Program

1 1 2002 python.jpg

$69.95

0130622214

C# How to Program

1 1 2002 cshtp.jpg

$69.95

0130341517

Java How to Program

4 1 2002 jhtp4.jpg

$69.95

0130649341

The Complete Java Training Course

4 2 2002 javactc4.jpg

$109.95

0130895601

Advanced Java 2 Platform How to Program

1 1 2002 advjhtp1.jpg

$69.95

0130308978

Internet and World Wide Web How to Program

2 1 2002 iw3htp2.jpg

$69.95

0130293636

Visual Basic .NET How to Program

2 1 2002 vbnet.jpg

$69.95

0130895636

The Complete C++ Training Course

3 2 2001 cppctc3.jpg

$109.95

0130895512

The Complete e-Business & e-Commerce Programming Training Course

1 2 2001 ebecctc.jpg

$109.95

Fig. 19.10 Data from the Titles table of Books.


15


013089561X

The Complete Internet & World Wide Web Programming Training Course

2 2 2001 iw3ctc2.jpg

$109.95

0130895547

The Complete Perl Training Course

1 2 2001 perl.jpg $109.95

0130895563

The Complete XML Programming Training Course

1 2 2001 xmlctc.jpg

$109.95

0130895725

C How to Program

3 1 2001 chtp3.jpg

$69.95

0130895717

C++ How to Program

3 1 2001 cpphtp3.jpg

$69.95

013028419X

e-Business and e-Commerce How to Program

1 1 2001 ebechtp1.jpg

$69.95

0130622265

Wireless Internet and Mobile Business How to Program

1 1 2001 wireless.jpg

$69.95

0130284181

Perl How to Program

1 1 2001 perlhtp1.jpg

$69.95

0130284173

XML How to Program

1 1 2001 xmlhtp1.jpg

$69.95



16


0130856118

The Complete Internet and World Wide Web Programming Training Course

1 2 2000 iw3ctc1.jpg

$109.95

0130125075

Java How to Program (Java 2)

3 1 2000 jhtp3.jpg

$69.95

0130852481

The Complete Java 2 Training Course


$109.95

0130323640

e-Business and e-Commerce for Managers

1 1 2000 ebecm.jpg

$69.95

0130161438

Internet and World Wide Web How to Program

1 1 2000 iw3htp1.jpg

$69.95

0130132497

Getting Started with Visual C++ 6 with an Introduction to MFC

1 1 1999 gsvc.jpg $49.95

0130829293

The Complete Visual Basic 6 Training Course

1 2 1999 vbctc1.jpg

$109.95

0134569555

Visual Basic 6 How to Program

1 1 1999 vbhtp1.jpg

$69.95

0132719746

Java Multimedia Cyber Classroom

1 2 1998 javactc.jpg

$109.95



17


0136325890

Java How to Program

1 1 1998 jhtp1.jpg $0.00

0139163050

The Complete C++ Training Course

2 2 1998 cppctc2.jpg

$109.95

0135289106

C++ How to Program


$49.95

0137905696

The Complete Java Training Course


$109.95

0130829277

The Complete Java Training Course (Java 1.1)


$99.95

0138993947

Java How to Program (Java 1.1)

2 1 1998 jhtp2.jpg $49.95

0131173340

C++ How to Program


$69.95

0132261197

C How to Program

2 1 1994 chtp2.jpg $49.95

0131180436

C How to Program

1 1 1992 chtp.jpg $69.95




18


Fig. 19.11 Table relationships in Books.

AuthorISBN

authorID

isbn

AuthorsauthorID

firstNamelastName

Publishers

publisherID

publisherName

Titles

isbn

titleeditionNumber

copyright

publisherIDimageFile

price

1

11


19

19.4 Structured Query Language (SQL)

• Used to request data (perform queries) and manipulate data


20

19.4 Structured Query Language (SQL)

SQL keyword Description SELECT Select (retrieve) fields from one or more tables.

FROM Tables from which to get fields or delete records. Required in every SELECT and DELETE.

WHERE Criteria for selection that determine the rows to be retrieved.

INNER JOIN Join records from multiple tables to produce a single set of records.

GROUP BY Criteria for grouping records.

ORDER BY Criteria for ordering records.

INSERT Insert data into a specified table.

UPDATE Update data in a specified table

DELETE Delete data from a specified table.

Fig. 19.12 SQL query keywords.

Fig. 19.12 SQL query keywords.


21

19.4.1Basic Select Query

• Extracts information from one or more tables in a database

• Format:– Basic: SELECT * FROM tableName

– Example: SELECT * FROM Authors

– * extracts all columns

– To get specific fields use a comma separated list instead of *


22

19.4.1 Basic Select Query

authorID lastName 1 Deitel

2 Deitel

3 Nieto

4 Steinbuhler

5 Santry

6 Lin

7 Sadhu

8 McPhie

9 Yaeger

10 Zlatkina

11 Wiedermann

12 Liperi

Fig. 19.13 authorID and lastName from the Authors table.

Fig. 19.13 authorID and lastName from the Authors table.


23

19.4.2 Where Clause

• Used to specify certain criteria in a query• Basic form:

– SELECT * FROM tableName WHERE criteria

• Example:– SELECT * FROM Titles WHERE copyright > 1999

• Can use LIKE clause– Used for pattern matching

• Uses wildcards

– *: zero or more characters take its place

– ?: exactly one character takes its place


24

19.4.2 WHERE Clause

Title editionNumber copyright Internet and World Wide Web How to Program 2 2002

Java How to Program 4 2002

The Complete Java Training Course 4 2002

The Complete e-Business & e-Commerce Programming Training Course

1 2001

The Complete Internet & World Wide Web Programming Training Course

2 2001

The Complete Perl Training Course 1 2001

The Complete XML Programming Training Course 1 2001

C How to Program 3 2001

C++ How to Program 3 2001

The Complete C++ Training Course 3 2001

e-Business and e-Commerce How to Program 1 2001

Internet and World Wide Web How to Program 1 2000

The Complete Internet and World Wide Web Programming Training Course

1 2000

Java How to Program (Java 2) 3 2000

The Complete Java 2 Training Course 3 2000

XML How to Program 1 2001

Perl How to Program 1 2001

Advanced Java 2 Platform How to Program 1 2002

e-Business and e-Commerce for Managers 1 2000

Wireless Internet and Mobile Business How to Program 1 2001

C# How To Program 1 2002

Python How to Program 1 2002

Visual Basic .NET How to Program 2 2002

Fig. 19.14 Titles with copyrights after 1999 from table Titles.

Fig. 19.14 Titles with copyrights after 1999 from table Titles.


25

19.4.2 WHERE Clause

authorID firstName lastName

1 Harvey Deitel

2 Paul Deitel

Fig. 19.15 Authors whose last names start with D from the Authors table.

Fig. 19.15 Authors whose last names start with D from the Authors table.

authorID firstName lastName 3 Tem Nieto

6 Ted Lin

11 Ben Wiedermann

12 Jonathan Liperi

Fig. 19.16 The authors from the Authors table whose last names contain i as their second letter.

Fig. 19.16 The authors from the Authors table whose last names contain i as their second letter.


26

19.4.3 ORDER BY Clause

• Used to arrange results of a query– Can be ascending or descending order

• Uses ASC and DESC respectively

• Example:– SELECT authorID FROM Authors ORDER BY authorID ASC

• Can be used to sort by multiple fields


27


authorID firstName lastName 2 Paul Deitel

1 Harvey Deitel

6 Ted Lin

12 Jonathan Liperi

8 David McPhie

3 Tem Nieto

7 Praveen Sadhu

5 Sean Santry

4 Kate Steinbuhler

11 Ben Wiedermann

9 Cheryl Yaeger

10 Marina Zlatkina

Fig. 19.17 Authors from table Authors in ascending order by lastName.

Fig. 19.17 Authors from table Authors in ascending order by lastName.


28


authorID firstName lastName 10 Marina Zlatkina

9 Cheryl Yaeger

11 Ben Wiedermann

4 Kate Steinbuhler

5 Sean Santry

7 Praveen Sadhu

3 Tem Nieto

8 David McPhie

12 Jonathan Liperi

6 Ted Lin

2 Paul Deitel

1 Harvey Deitel

Fig. 19.18 Authors from table Authors in descending order by lastName.

Fig. 19.18 Authors from table Authors in descending order by lastName.


29


authorID firstName lastName 1 Harvey Deitel

2 Paul Deitel

6 Ted Lin

12 Jonathan Liperi

8 David McPhie

3 Tem Nieto

7 Praveen Sadhu

5 Sean Santry

4 Kate Steinbuhler

11 Ben Wiedermann

9 Cheryl Yaeger

10 Marina Zlatkina

Fig. 19.19 Authors from table Authors in ascending order by lastName and by firstName.

Fig. 19.19 Authors from table Authors in ascending order by lastName and by firstName.


30


isbn title edition-Number

copy-right price

0130895601 Advanced Java 2 Platform How to Program

1 2002 $69.95

0131180436 C How to Program 1 1992 $69.95

0130895725 C How to Program 3 2001 $69.95

0132261197 C How to Program 2 1994 $49.95

0130622214 C# How To Program 1 2002 $69.95

0135289106 C++ How to Program 2 1998 $49.95

0131173340 C++ How to Program 1 1994 $69.95

0130895717 C++ How to Program 3 2001 $69.95

013028419X e-Business and e-Commerce How to Program

1 2001 $69.95

0130308978 Internet and World Wide Web How to Program

2 2002 $69.95

0130161438 Internet and World Wide Web How to Program

1 2000 $69.95

0130341517 Java How to Program 4 2002 $69.95

0136325890 Java How to Program 1 1998 $0.00

0130284181 Perl How to Program 1 2001 $69.95

0130923613 Python How to Program 1 2002 $69.95

0130293636 Visual Basic .NET How to Program

2 2002 $69.95

0134569555 Visual Basic 6 How to Program

1 1999 $69.95

0130622265 Wireless Internet and Mobile Business How to Program

1 2001 $69.95

0130284173 XML How to Program 1 2001 $69.95

Fig. 19.20 Books from table Titles whose titles end with How to Program in ascending order by title.

Fig. 19.20 Books from table Titles whose titles end with How to Program in ascending order by title.


31

19.4.4 Merging Data from Multiple Tables: INNER JOIN

• INNER JOIN – Merges records from multiple tables into a single record

– Tests for matching values in a common field

– General Form: SELECT * FROM table1 INNER JOIN table2 ON table1.fieldName=table2.fieldName

– Example: SELECT firstName, isbn FROM Authors INNER JOIN AuthorISBN ON Authors.authorID= AuthorISBN.authorID

• Fully-qualified names use the table name and dot operator followed by the field name


32

19.4.4 Merging Data from Multiple Tables: INNER JOIN

firstName lastName isbn firstName lastName isbn

Harvey Deitel 0130895601 Paul Deitel 0134569555







Harvey Deitel 0138993947 Paul Deitel 013028419x




Harvey Deitel 013028419x Paul Deitel 0132261197


Harvey Deitel 0135289106 Tem Nieto 0130284181




Paul Deitel 0130895601 Tem Nieto 0130856118

Paul Deitel 0130284181 Tem Nieto 0130161438

Paul Deitel 0130284173 Tem Nieto 013028419x

Paul Deitel 0130829293 Sean Santry 0130895601

Fig. 19.21 Portion of the authors and the ISBN numbers for the books they have written in ascending order by lastName and firstName.

Fig. 19.21 Portion of the authors and the ISBN numbers for the books they have written in ascending order by lastName and firstName.


3319.4.5 Joining Data from Tables Authors, AuthorISBN, Titles and

Publishers• Tables produced by INNER JOIN can be used as

arguments for another INNER JOIN



Publishers

1 SELECT Titles.title, Titles.isbn, Authors.firstName, 2 Authors.lastName, Titles.copyright, 3 Publishers.publisherName4 FROM5 ( Publishers INNER JOIN Titles 6 ON Publishers.publisherID = Titles.publisherID ) 7 INNER JOIN8 ( Authors INNER JOIN AuthorISBN 9 ON Authors.authorID = AuthorISBN.authorID ) 10 ON Titles.isbn = AuthorISBN.isbn11 ORDER BY Titles.title

Fig. 19.22 TitleAuthor query of Books database.

Join Publishers and Titles tables if the publisherID matches

Join Authors and AuthorISBN if authorID matches

Join two created tables if titlesISBN matches authorsISBN

Sort new table by title



PublishersTitle isbn first-

Name last-Name

copy-right

publisher-Name


0130895601 Paul Deitel 2002 Prentice Hall


0130895601 Harvey Deitel 2002 Prentice Hall


0130895601 Sean Santry 2002 Prentice Hall

C How to Program 0131180436 Harvey Deitel 1992 Prentice Hall

C How to Program 0131180436 Paul Deitel 1992 Prentice Hall





C# How To Program 0130622214 Tem Nieto 2002 Prentice Hall

C# How To Program 0130622214 Paul Deitel 2002 Prentice Hall

C# How To Program 0130622214 Cheryl Yaeger 2002 Prentice Hall

C# How To Program 0130622214 Marina Zlatkina 2002 Prentice Hall

C# How To Program 0130622214 Harvey Deitel 2002 Prentice Hall

C++ How to Program 0130895717 Paul Deitel 2001 Prentice Hall

C++ How to Program 0130895717 Harvey Deitel 2001 Prentice Hall





Fig. 19.23 Portion of the result set produced by the query in Fig. 19.22.



Publishers


0130323640 Harvey Deitel 2000 Prentice Hall


0130323640 Kate Steinbuhler

2000 Prentice Hall


0130323640 Paul Deitel 2000 Prentice Hall


013028419X Harvey Deitel 2001 Prentice Hall


013028419X Paul Deitel 2001 Prentice Hall


013028419X Tem Nieto 2001 Prentice Hall




37

19.4.6 Insert Statement

• Inserts a new record into a table• Form: INSERT INTO tableName(fieldName1) VALUES (value1)

• Values must match field names in order and type


38

19.4.6 INSERT Statement


2 Paul Deitel

3 Tem Nieto

4 Kate Steinbuhler

5 Sean Santry

6 Ted Lin

7 Praveen Sadhu

8 David McPhie

9 Cheryl Yaeger

10 Marina Zlatkina

11 Ben Wiedermann

12 Jonathan Liperi

13 Sue Smith

Fig. 19.24 Table Authors after an INSERT INTO operation to add a record.

Fig. 19.24 Table Authors after an INSERT INTO operation to add a record.


39

19.4.7 UPDATE Statement

• Modifies data in a table• Form: UPDATE tableName SET fieldName1 =

value1 WHERE criteria


40

19.4.7 UPDATE Statement


2 Paul Deitel

3 Tem Nieto

4 Kate Steinbuhler

5 Sean Santry

6 Ted Lin

7 Praveen Sadhu

8 David McPhie

9 Cheryl Yaeger

10 Marina Zlatkina

11 Ben Wiedermann

12 Jonathan Liperi

13 Sue Jones

Fig. 19.25 Table Authors after an UPDATE operation to change a record.

Fig. 19.25 Table Authors after an UPDATE operation to change a record.


41

19.4.8 DELETE Statement

• Removes data from a table• Form: DELETE FROM tableName WHERE criteria


42

19.4.8 DELETE Statement


2 Paul Deitel

3 Tem Nieto

4 Kate Steinbuhler

5 Sean Santry

6 Ted Lin

7 Praveen Sadhu

8 David McPhie

9 Cheryl Yaeger

10 Marina Zlatkina

11 Ben Wiedermann

12 Jonathan Liperi

Fig. 19.26 Table Authors after a DELETE operation to remove a record.

Fig. 19.26 Table Authors after a DELETE operation to remove a record.


43

19.5 ADO .NET and Object Model

• Provides an API for accessing database systems programmatically

• Namespaces:– System.Data

• System.Data.DataSet: DataTables and their relationships represent a cache of data. Store data from source in local memory

– System.Data.OleDb: classes to work with any datasource• OleDbConnection: a connect to a datasource• OleDbDataAdapter: connect to a datasource through an instance of

OleDbConnection and can populate DataSet with data from a datasource • OleDbCommand: represent a SQL command to be executed on a

datasource. Do not cache data in local memory

– System.Data.SqlClient: classes that are optimized to work with MS SQL Server 2000


4419.6 Programming with ADO .NET: Extracting Information from a DBMS

• Examples that demonstrate how to connect to a database, query the database and display the results of the query1. 工具 -> 連接資料庫

– MicroSoft Jet 4.0 OLE DB Provider

– 選擇 Access 資料庫2. 在 “伺服器總管” 拖曳資料庫至表單以產生

OldDbConnection1

3. 在 “資料” 拖曳 OldDbDataAdapter 至表單 , 在精靈的問項保留預設值 , 按 “查詢產生器” , 選擇 Authors 表格 , 在 ‘ *’ 左邊打

4. 在 “資料” 拖曳 DataSet, 選擇 “不具型別資料集”5. 在程式碼第 12 行 ( initializeComponent ) 之後加上 OleDbDataAdapter1.Fill(DataSet1, "Authors")

DataGrid1.SetDataBinding(DataSet1, "Authors")


45

19.6.1 Connecting to and Querying an Access Data Source

• Retrieves data and stores it in a DataGrid

2002 Prentice Hall.All rights reserved.

Outline46

DisplayTable.vb

1 ' Fig. 19.27: DisplayTable.vb2 ' Displaying data from a database table.3 4 Public Class FrmTableDisplay5 Inherits System.Windows.Forms.Form6 7 #Region " Windows Form Designer generated code "8 9 Public Sub New()10 MyBase.New()11 12 ' This call is required by the Windows Form Designer.13 InitializeComponent()14 15 ' Add any initialization after the 16 ' InitializeComponent() call17 18 ' fill DataSet11 with data19 OleDbDataAdapter1.Fill(DataSet1, "Authors")20 21 ' bind data in Users table in dataSet11 to dgdAuthors22 dgdAuthors.SetDataBinding(DataSet1, "Authors")23 End Sub ' New24 25 ' Form overrides dispose to clean up the component list.26 Protected Overloads Overrides Sub Dispose( _27 ByVal disposing As Boolean)28 29 If disposing Then30 If Not (components Is Nothing) Then31 components.Dispose()32 End If33 End If34 MyBase.Dispose(disposing)35 End Sub ' Dispose

Constructor to populate dataSet1

Call method fill to retrieve data from database associated with oleDbConnection

Bind DataGrid to data source


Outline47

DisplayTable.vb

36 37 Friend WithEvents dgdAuthors As System.Windows.Forms.DataGrid38 Friend WithEvents OleDbSelectCommand1 As _39 System.Data.OleDb.OleDbCommand40 41 Friend WithEvents OleDbInsertCommand1 As _42 System.Data.OleDb.OleDbCommand43 44 Friend WithEvents OleDbUpdateCommand1 As _45 System.Data.OleDb.OleDbCommand46 47 Friend WithEvents OleDbDeleteCommand1 As _48 System.Data.OleDb.OleDbCommand49 50 Friend WithEvents OleDbConnection1 As _51 System.Data.OleDb.OleDbConnection52 53 Friend WithEvents OleDbDataAdapter1 As _54 System.Data.OleDb.OleDbDataAdapter55 56 Friend WithEvents DataSet1 As System.Data.DataSet57 58 ' Required by the Windows Form Designer59 Private components As System.ComponentModel.Container60 61 ' NOTE: The following procedure is required by the 62 ' Windows Form Designer63 ' It can be modified using the Windows Form Designer. 64 ' Do not modify it using the code editor.65 <System.Diagnostics.DebuggerStepThrough()> _66 Private Sub InitializeComponent()67 68 Me.dgdAuthors = New System.Windows.Forms.DataGrid()69 Me.OleDbSelectCommand1 = _70 New System.Data.OleDb.OleDbCommand()


Outline48

DisplayTable.vb

71 72 Me.OleDbInsertCommand1 = _73 New System.Data.OleDb.OleDbCommand()74 75 Me.OleDbUpdateCommand1 = _76 New System.Data.OleDb.OleDbCommand()77 78 Me.OleDbDeleteCommand1 = _79 New System.Data.OleDb.OleDbCommand()80 81 Me.OleDbConnection1 = _82 New System.Data.OleDb.OleDbConnection()83 84 Me.OleDbDataAdapter1 = _85 New System.Data.OleDb.OleDbDataAdapter()86 87 Me.DataSet1 = New System.Data.DataSet()88 CType(Me.dgdAuthors, _89 System.ComponentModel.ISupportInitialize).BeginInit()90 91 CType(Me.DataSet1, _92 System.ComponentModel.ISupportInitialize).BeginInit()93 94 Me.SuspendLayout()95 96 '97 ' dgdAuthors98 '99 Me.dgdAuthors.DataMember = ""100 Me.dgdAuthors.Location = New System.Drawing.Point(8, 8)101 Me.dgdAuthors.Name = "dgdAuthors"102 Me.dgdAuthors.Size = New System.Drawing.Size(304, 256)103 Me.dgdAuthors.TabIndex = 0104


Outline49

DisplayTable.vb

105 '106 ' OleDbSelectCommand1107 '108 Me.OleDbSelectCommand1.CommandText = _109 "SELECT authorID, firstName, lastName FROM Authors"110 111 Me.OleDbSelectCommand1.Connection = Me.OleDbConnection1112 113 '114 ' OleDbInsertCommand1115 '116 Me.OleDbInsertCommand1.CommandText = _117 "INSERT INTO Authors(authorID, firstName, lastName)" & _118 "VALUES (?, ?, ?)"119 120 Me.OleDbInsertCommand1.Connection = _121 Me.OleDbConnection1122 123 Me.OleDbInsertCommand1.Parameters.Add _124 (New System.Data.OleDb.OleDbParameter("authorID", _125 System.Data.OleDb.OleDbType.Numeric, 0, _126 System.Data.ParameterDirection.Input, False, _127 CType(10, Byte), CType(0, Byte), "authorID", _128 System.Data.DataRowVersion.Current, Nothing))129 130 Me.OleDbInsertCommand1.Parameters.Add _131 (New System.Data.OleDb.OleDbParameter("firstName", _132 System.Data.OleDb.OleDbType.Char, 50, _133 System.Data.ParameterDirection.Input, False, _134 CType(0, Byte), CType(0, Byte), "firstName", _135 System.Data.DataRowVersion.Current, Nothing))136


Outline50

DisplayTable.vb

137 Me.OleDbInsertCommand1.Parameters.Add _138 (New System.Data.OleDb.OleDbParameter("lastName", _139 System.Data.OleDb.OleDbType.Char, 50, _140 System.Data.ParameterDirection.Input, False, _141 CType(0, Byte), CType(0, Byte), "lastName", _142 System.Data.DataRowVersion.Current, Nothing))143 144 '145 ' OleDbUpdateCommand1146 '147 Me.OleDbUpdateCommand1.CommandText = _148 "UPDATE Authors SET authorID = ?, firstName = ?, " & _149 "lastName = ? WHERE (authorID = ?)" & _150 " AND (firstName = ?) AND (lastName = ?)"151 152 Me.OleDbUpdateCommand1.Connection = Me.OleDbConnection1153 Me.OleDbUpdateCommand1.Parameters.Add _154 (New System.Data.OleDb.OleDbParameter("authorID", _155 System.Data.OleDb.OleDbType.Numeric, 0, _156 System.Data.ParameterDirection.Input, False, _157 CType(10, Byte), CType(0, Byte), "authorID", _158 System.Data.DataRowVersion.Current, Nothing))159 160 Me.OleDbUpdateCommand1.Parameters.Add _161 (New System.Data.OleDb.OleDbParameter("firstName", _162 System.Data.OleDb.OleDbType.Char, 50, _163 System.Data.ParameterDirection.Input, False, _164 CType(0, Byte), CType(0, Byte), "firstName", _165 System.Data.DataRowVersion.Current, Nothing))166

Set connection property for oleDbUpdateCommand1

Set CommandText for oleDbUpdateCommand1


Outline51

DisplayTable.vb

167 Me.OleDbUpdateCommand1.Parameters.Add _168 (New System.Data.OleDb.OleDbParameter("lastName", _169 System.Data.OleDb.OleDbType.Char, 50, _170 System.Data.ParameterDirection.Input, False, _171 CType(0, Byte), CType(0, Byte), "lastName", _172 System.Data.DataRowVersion.Current, Nothing))173 174 Me.OleDbUpdateCommand1.Parameters.Add _175 (New System.Data.OleDb.OleDbParameter _176 ("Original_authorID", _177 System.Data.OleDb.OleDbType.Numeric, 0, _178 System.Data.ParameterDirection.Input, False, _179 CType(10, Byte), CType(0, Byte), "authorID", _180 System.Data.DataRowVersion.Original, Nothing))181 182 Me.OleDbUpdateCommand1.Parameters.Add _183 (New System.Data.OleDb.OleDbParameter _184 ("Original_firstName", _185 System.Data.OleDb.OleDbType.Char, 50, _186 System.Data.ParameterDirection.Input, False, _187 CType(0, Byte), CType(0, Byte), "firstName", _188 System.Data.DataRowVersion.Original, Nothing))189 190 Me.OleDbUpdateCommand1.Parameters.Add _191 (New System.Data.OleDb.OleDbParameter _192 ("Original_lastName", _193 System.Data.OleDb.OleDbType.Char, 50, _194 System.Data.ParameterDirection.Input, False, _195 CType(0, Byte), CType(0, Byte), "lastName", _196 System.Data.DataRowVersion.Original, Nothing))197


Outline52

DisplayTable.vb

198 '199 ' OleDbDeleteCommand1200 '201 Me.OleDbDeleteCommand1.CommandText = _202 "DELETE FROM Authors WHERE (authorID = ?) AND " & _203 "(firstName = ?) AND (lastName = ?)"204 205 Me.OleDbDeleteCommand1.Connection = Me.OleDbConnection1206 Me.OleDbDeleteCommand1.Parameters.Add _207 (New System.Data.OleDb.OleDbParameter("authorID", _208 System.Data.OleDb.OleDbType.Numeric, 0, _209 System.Data.ParameterDirection.Input, False, _210 CType(10, Byte), CType(0, Byte), "authorID", _211 System.Data.DataRowVersion.Original, Nothing))212 213 Me.OleDbDeleteCommand1.Parameters.Add _214 (New System.Data.OleDb.OleDbParameter("firstName", _215 System.Data.OleDb.OleDbType.Char, 50, _216 System.Data.ParameterDirection.Input, False, _217 CType(0, Byte), CType(0, Byte), "firstName", _218 System.Data.DataRowVersion.Original, Nothing))219 220 Me.OleDbDeleteCommand1.Parameters.Add _221 (New System.Data.OleDb.OleDbParameter("lastName", _222 System.Data.OleDb.OleDbType.Char, 50, _223 System.Data.ParameterDirection.Input, False, _224 CType(0, Byte), CType(0, Byte), "lastName", _225 System.Data.DataRowVersion.Original, Nothing))226


Outline53

DisplayTable.vb

227 '228 'OleDbConnection1229 '230 Me.OleDbConnection1.ConnectionString = _231 "Provider=Microsoft.Jet.OLEDB.4.0;Password="""";" & _232 "User ID=Admin;Data Source=C:\Documen" & _233 "ts and Settings\thiago\Desktop\vbhtp2e\examples\" & _234 "Ch19\Fig19_27\Books.mdb;Mode=Sha" & _235 "re Deny None;Extended Properties="""";" & _236 "Jet OLEDB:System database="""";Jet OLEDB:Regis" & _237 "try Path="""";Jet OLEDB:Database Password="""";" & _238 "Jet OLEDB:Engine Type=5;Jet OLEDB:Dat" & _239 "abase Locking Mode=1;Jet OLEDB:Global Partial " & _240 "Bulk Ops=2;Jet OLEDB:Global Bulk T" & _241 "ransactions=1;Jet OLEDB:New Database " & _242 "Password="""";Jet OLEDB:Create System Databas" & _243 "e=False;Jet OLEDB:Encrypt Database=False;" & _244 "Jet OLEDB:Don't Copy Locale on Compact=" & _245 "False;Jet OLEDB:Compact Without Replica " & _246 "Repair=False;Jet OLEDB:SFP=False"247 248 '249 ' OleDbDataAdapter1250 '251 Me.OleDbDataAdapter1.DeleteCommand = _252 Me.OleDbDeleteCommand1253 254 Me.OleDbDataAdapter1.InsertCommand = _255 Me.OleDbInsertCommand1256 257 Me.OleDbDataAdapter1.SelectCommand = _258 Me.OleDbSelectCommand1259

Initialize oleDbConnection, and specify path to database

Specify how oleDbDataAdapter deletes data

Specify how oleDbDataAdapter inserts data

Specify how oleDbDataAdapter selects data


Outline54

DisplayTable.vb

260 Me.OleDbDataAdapter1.TableMappings.AddRange _261 (New System.Data.Common.DataTableMapping() _262 {New System.Data.Common.DataTableMapping("Table", _263 "Authors", New System.Data.Common.DataColumnMapping() _264 {New System.Data.Common.DataColumnMapping("authorID", _265 "authorID"), New System.Data.Common.DataColumnMapping _266 ("firstName", "firstName"), _267 New System.Data.Common.DataColumnMapping("lastName", _268 "lastName")})})269 270 Me.OleDbDataAdapter1.UpdateCommand = _271 Me.OleDbUpdateCommand1272 273 '274 ' DataSet1275 '276 Me.DataSet1.DataSetName = "NewDataSet"277 Me.DataSet1.Locale = _278 New System.Globalization.CultureInfo("en-US")279 280 '281 ' FrmTableDisplay282 '283 Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)284 Me.ClientSize = New System.Drawing.Size(320, 273)285 Me.Controls.AddRange(New System.Windows.Forms.Control() _286 {Me.dgdAuthors})287 288 Me.Name = "FrmTableDisplay"289 Me.Text = "Table Display"290 CType(Me.dgdAuthors, System.ComponentModel. _291 ISupportInitialize).EndInit()292 293 CType(Me.DataSet1, System.ComponentModel. _294 ISupportInitialize).EndInit()

Specify how oleDbDataAdapter updates data


Outline55

DisplayTable.vb

295 296 Me.ResumeLayout(False)297 298 End Sub ' InitializeComponent299 300 #End Region301 302 End Class ' FrmTableDisplay


56

19.6.2 Querying the Books Database

• Use SELECT statements on database and display results


Outline57

DisplayQueryResults.vb

1 ' Fig. 19.28: DisplayQueryResults.vb2 ' Displays the contents of the authors database.3 4 Public Class FrmDisplayQueryResult5 Inherits System.Windows.Forms.Form6 7 Friend WithEvents txtQuery As System.Windows.Forms.TextBox8 Friend WithEvents cmdSubmit As System.Windows.Forms.Button9 Friend WithEvents dgdResults As System.Windows.Forms.DataGrid10 Friend WithEvents BooksConnection As _11 System.Data.OleDb.OleDbConnection12 13 Friend WithEvents BooksDataAdapter As _14 System.Data.OleDb.OleDbDataAdapter15 16 Friend WithEvents BooksDataSet As System.Data.DataSet17 18 ' Visual Studio .NET generated code19 20 ' perform SQL query on data21 Private Sub cmdSubmit_Click(ByVal sender As System.Object, _22 ByVal e As System.EventArgs) Handles cmdSubmit.Click23 24 Try25 26 ' set the text of the SQL query to what the user typed27 ' in28 BooksDataAdapter.SelectCommand.CommandText = _29 txtQuery.Text30 31 ' clear the DataSet from the previous operation32 BooksDataSet.Clear()33

Form FrmDisplayQueryResult contains TextBox txtQuery, in which users input SELECT statements

After entering a query, the user clicks Button cmdSubmit, labeled Submit Query, to view the results of the query


Outline58

DisplayQueryResults.vb

Program Output

34 ' Fill the data set with the information that results35 ' from the SQL query36 BooksDataAdapter.Fill(BooksDataSet, "Authors")37 38 ' Bind the DataGrid to the contents of the DatSet39 dgdResults.SetDataBinding(BooksDataSet, "Authors")40 41 ' display database connection verbose message42 Catch exception As System.Data.OleDb.OleDbException43 MessageBox.Show("Invalid Query")44 End Try45 46 End Sub ' cmdSubmit_Click47 48 End Class ' FrmDisplayQueryResults


59

19.7 Programming with ADO.NET: Modifying a DBMS

• Example implements an address book– User can insert, locate and update records


Outline60

AddressBook.vb

1 ' Fig. 19.29: AddressBook.vb2 ' Using SQL statements to manipulate a database.3 4 Imports System.Windows.Forms5 6 Public Class FrmAddressBook7 Inherits Form8 9 ' top set of command buttons10 Friend WithEvents cmdFind As Button11 Friend WithEvents cmdAdd As Button12 Friend WithEvents cmdUpdate As Button13 Friend WithEvents cmdClear As Button14 Friend WithEvents cmdHelp As Button15 16 ' textbox identifier labels17 Friend WithEvents lblId As Label18 Friend WithEvents lblFirst As Label19 Friend WithEvents lblLast As Label20 Friend WithEvents lblAddress As Label21 Friend WithEvents lblCity As Label22 Friend WithEvents lblState As Label23 Friend WithEvents lblZip As Label24 Friend WithEvents lblCountry As Label25 Friend WithEvents lblEmail As Label26 Friend WithEvents lblPhone As Label27 Friend WithEvents lblFax As Label28 29 ' input textboxes30 Friend WithEvents txtId As TextBox31 Friend WithEvents txtFirst As TextBox32 Friend WithEvents txtLast As TextBox33 Friend WithEvents txtAddress As TextBox34 Friend WithEvents txtCity As TextBox35 Friend WithEvents txtState As TextBox


Outline61

AddressBook.vb

36 Friend WithEvents txtZip As TextBox37 Friend WithEvents txtCountry As TextBox38 Friend WithEvents txtEmail As TextBox39 Friend WithEvents txtPhone As TextBox40 Friend WithEvents txtFax As TextBox41 42 ' query status display textbox43 Friend WithEvents txtStatus As TextBox44 45 ' database connection 46 Friend WithEvents AddressBookConnection As _47 System.Data.OleDb.OleDbConnection48 49 ' database adapter 50 Friend WithEvents AddressBookDataAdapter As _51 System.Data.OleDb.OleDbDataAdapter52 53 ' query dataset 54 Friend WithEvents AddressBookDataSet As System.Data.DataSet55 56 ' constructor57 Public Sub New()58 MyBase.New()59 60 ' This call is required by the Windows Form Designer.61 InitializeComponent()62 63 ' Add any initialization after the InitializeComponent call64 65 ' open connection66 AddressBookConnection.Open()67 End Sub ' New68 69 ' Visual Studio .NET generated code70


Outline62

AddressBook.vb

71 ' finds record in database72 Private Sub cmdFind_Click(ByVal sender As System.Object, _73 ByVal e As System.EventArgs) Handles cmdFind.Click74 75 Try76 77 ' ensure user input last name78 If txtLast.Text <> "" Then79 80 ' clear DataSet from last operation81 AddressBookDataSet.Clear()82 83 ' create SQL query to find contact84 ' with specified last name85 AddressBookDataAdapter.SelectCommand.CommandText = _86 "SELECT * FROM addresses WHERE " & _87 "lastname = '" & txtLast.Text & "' "88 89 ' fill AddressBookDataSet with the rows resulting 90 ' from the query91 AddressBookDataAdapter.Fill(AddressBookDataSet)92 93 ' display information94 Display(AddressBookDataSet)95 txtStatus.Text &= vbCrLf & "Query Successful " & _96 vbCrLf97 98 ' prompt user for last name99 Else100 txtLast.Text = _101 "Enter last name here then press Find"102 End If103 104 ' display verbose information with database exception105 Catch oleDbExceptionParameter As _

Method Clear of class DataSet is invoked to empty the DataSet of any prior data

The TextBoxes are updated with a call to method Display

Event handler cmdFind_Click performs the SELECT query on the database for the record associated with the String entered in txtLast


Outline63

AddressBook.vb

106 System.Data.OleDb.OleDbException107 108 Console.WriteLine(oleDbExceptionParameter.StackTrace)109 txtStatus.Text &= oleDbExceptionParameter.ToString110 111 ' display message box when invalid operation112 Catch invalidOperationExceptionParameter As _113 InvalidOperationException114 115 MessageBox.Show( _116 invalidOperationExceptionParameter.Message)117 End Try118 119 End Sub ' cmdFind_Click120 121 ' adds record to database122 Private Sub cmdAdd_Click(ByVal sender As System.Object, _123 ByVal e As System.EventArgs) Handles cmdAdd.Click124 125 Try126 127 ' ensure first and last name input128 If (txtLast.Text <> "" AndAlso txtFirst.Text <> "") Then129 130 ' create the SQL query to insert a row131 AddressBookDataAdapter.InsertCommand.CommandText = _132 "INSERT INTO addresses(firstname, " & _133 "lastname, address, city, " & _134 "stateorprovince, postalcode, country, " & _135 "emailaddress, homephone, faxnumber) " & _136 "VALUES('" & txtFirst.Text & "' , " & _137 "'" & txtLast.Text & "' , " & _138 "'" & txtAddress.Text & "' , " & _139 "'" & txtCity.Text & "' , " & _140 "'" & txtState.Text & "' , " & _

Method cmdAdd_Click performs INSERT and UPDATE operations


Outline64

AddressBook.vb

141 "'" & txtZip.Text & "' , " & _142 "'" & txtCountry.Text & "' , " & _143 "'" & txtEmail.Text & "' , " & _144 "'" & txtPhone.Text & "' , " & _145 "'" & txtFax.Text & "')"146 147 ' notify the user the query is being sent 148 txtStatus.Text &= vbCrLf & "Sending query: " & _149 AddressBookDataAdapter.InsertCommand. _ 150 CommandText & vbCrLf151 152 ' send query153 AddressBookDataAdapter.InsertCommand. _154 ExecuteNonQuery()155 156 txtStatus.Text &= vbCrLf & "Query successful"157 158 ' prompt user to input first and last name159 Else160 txtStatus.Text &= vbCrLf & _161 "Enter at least first and last name then " & _162 "press Add" & vbCrLf163 End If164 165 ' display verbose information when database exception166 Catch oleDbExceptionParameter As _167 System.Data.OleDb.OleDbException168 169 Console.WriteLine(oleDbExceptionParameter.StackTrace)170 txtStatus.Text &= oleDbExceptionParameter.ToString171 End Try172 173 End Sub ' cmdAdd_Click174 175 ' updates entry in database


Outline65

AddressBook.vb

176 Private Sub cmdUpdate_Click(ByVal sender As System.Object, _177 ByVal e As System.EventArgs) Handles cmdUpdate.Click178 179 Try180 181 ' make sure user has already found 182 ' record to update183 If txtId.Text <> "" Then184 185 ' set SQL query to update all fields in 186 ' table where id number matches id in 187 ' idTextBox188 AddressBookDataAdapter.UpdateCommand.CommandText = _189 "UPDATE addresses SET firstname=" & _190 "'" & txtFirst.Text & "' , " & _191 "lastname = '" & txtLast.Text & "' , " & _192 "address='" & txtAddress.Text & "' , " & _193 "city='" & txtCity.Text & "' , " & _194 "stateorprovince= " & _195 "'" & txtState.Text & "', " & _196 "postalcode='" & txtZip.Text & "', " & _197 "country='" & txtCountry.Text & "' , " & _198 "emailaddress='" & txtEmail.Text & "' , " & _199 "homephone='" & txtPhone.Text & "' , " & _200 "faxnumber='" & txtFax.Text & "' " & _201 "WHERE id=" & txtId.Text & " ; "202203 ' notify user that query is being sent204 txtStatus.Text &= vbCrLf & "Sending query: " & _205 AddressBookDataAdapter.UpdateCommand. _206 CommandText & vbCrLf207208 ' execute query209 AddressBookDataAdapter.UpdateCommand. _210 ExecuteNonQuery()


Outline66

AddressBook.vb

211212 txtStatus.Text &= vbCrLf & "Query Successful" & _213 vbCrLf214215 ' prompt user to input existing record216 Else217 txtStatus.Text &= vbCrLf & _218 "You may only update an existing record. " & _219 "Use Find to locate the record, then " & _220 "modify the information and press Update." & _221 vbCrLf222 End If223224 ' display verbose information when database exception225 Catch oleDbExceptionParameter As _226 System.Data.OleDb.OleDbException227228 Console.WriteLine(oleDbExceptionParameter.StackTrace)229 txtStatus.Text &= oleDbExceptionParameter.ToString230 End Try231232 End Sub ' cmdUpdate_Click233234 ' clears all information in textboxes235 Private Sub cmdClear_Click(ByVal sender As System.Object, _236 ByVal e As System.EventArgs) Handles cmdClear.Click237238 txtId.Clear()239 ClearTextBoxes()240 End Sub ' cmdClear_Click241242 ' displays information on application use243 Private Sub cmdHelp_Click(ByVal sender As System.Object, _244 ByVal e As System.EventArgs) Handles cmdHelp.Click245


Outline67

AddressBook.vb

246 txtStatus.AppendText(vbCrLf & _247 "Click Find to locate a record" & vbCrLf & _248 "Click Add to insert a new record." & vbCrLf & _249 "Click Update to update the information in a " & _250 "record " & vbCrLf & "Click Clear to empty the " & _ 251 "textboxes")252 End Sub ' cmdHelp_Click253254 ' displays data in dataset255 Private Sub Display(ByVal dataset As DataSet)256257 Try258259 ' get first DataTable - there will be one260 Dim dataTable As DataTable = dataset.Tables(0)261262 ' ensure dataTable not empty263 If dataTable.Rows.Count <> 0 Then264 Dim recordNumber As Integer = _265 Convert.ToInt32(dataTable.Rows(0)(0))266267 txtId.Text = recordNumber.ToString268 txtFirst.Text = _269 Convert.ToString(dataTable.Rows(0)(1))270271 txtLast.Text = _272 Convert.ToString(dataTable.Rows(0)(2))273274 txtAddress.Text = _275 Convert.ToString(dataTable.Rows(0)(3))276277 txtCity.Text = _278 Convert.ToString(dataTable.Rows(0)(4))279280 txtState.Text = _

Retrieve the remaining fields of data from the DataTable to populate the user interface

Retrieves the field with index 0, 0 and stores the value in variable recordNumber

Checks whether the query returned any rows

Method Display updates the user interface with data from the newly retrieved address book record


Outline68

AddressBook.vb

281 Convert.ToString(dataTable.Rows(0)(5))282283 txtZip.Text = _284 Convert.ToString(dataTable.Rows(0)(6))285286 txtCountry.Text = _287 Convert.ToString(dataTable.Rows(0)(7))288289 txtEmail.Text = _290 Convert.ToString(dataTable.Rows(0)(8))291292 txtPhone.Text = _293 Convert.ToString(dataTable.Rows(0)(9))294295 txtFax.Text = _296 Convert.ToString(dataTable.Rows(0)(10))297298 ' display not-found message299 Else300 txtStatus.Text &= vbCrLf & "No record found“ & vbCrLf301 End If302303 ' display verbose information when database exception304 Catch oleDbExceptionParameter As _305 System.Data.OleDb.OleDbException306307 Console.WriteLine(oleDbExceptionParameter.StackTrace)308 txtStatus.Text &= oleDbExceptionParameter.ToString309 End Try310311 End Sub ' Display 312313 ' clears text boxes314 Private Sub ClearTextBoxes()315 txtFirst.Clear()

The Clear button clears the text from the TextBoxes using method ClearTextBoxes


Outline69

AddressBook.vb

316 txtLast.Clear()317 txtAddress.Clear()318 txtCity.Clear()319 txtState.Clear()320 txtZip.Clear()321 txtCountry.Clear()322 txtEmail.Clear()323 txtPhone.Clear()324 txtFax.Clear()325 End Sub ' ClearTextBoxes326327 End Class ' FrmAddressBook


Outline70

AddressBook.vb


Outline71

AddressBook.vb


Outline72

AddressBook.vb


Outline73

AddressBook.vb


74

19.8 Reading and Writing XML Files

• ADO.NET can convert data from data source into XML files– Uses methods WriteXml, ReadXml andGetXml


Outline75

XMLWriter.vb

1 ' Fig. 19.30 XMLWriter.vb2 ' Demonstrates generating XML from an ADO.NET DataSet3 4 Public Class FrmXMLWriter5 Inherits System.Windows.Forms.Form6 7 ' constructor8 Public Sub New()9 MyBase.New()10 11 ' This call is required by the Windows Form Designer.12 InitializeComponent()13 14 ' Add any initialization after the 15 ' InitializeComponent() call16 17 ' open database connection18 BaseballConnection.Open()19 20 ' fill DataSet with data from OleDbDataAdapter21 BaseballDataAdapter.Fill(BaseballDataSet, "Players")22 23 ' bind DataGrid to DataSet24 dgdPlayers.SetDataBinding(BaseballDataSet, "Players")25 End Sub26 27 Friend WithEvents cmdWrite As System.Windows.Forms.Button28 Friend WithEvents dgdPlayers As System.Windows.Forms.DataGrid29 Friend WithEvents txtOutput As System.Windows.Forms.TextBox30 Friend WithEvents BaseballConnection As _31 System.Data.OleDb.OleDbConnection32 33 Friend WithEvents BaseballDataAdapter As _34 System.Data.OleDb.OleDbDataAdapter35

Establishes a connection to the Baseball databaseMethod Fill of class OleDbDataAdapter is called to populate BaseballDataSet with data from the Players table in the Baseball database

Binds the dgdPlayers to BaseballDataSet to display the information to the user


Outline76

XMLWriter.vb

36 Friend WithEvents BaseballDataSet As System.Data.DataSet37 38 ' Visual Studio .NET generated code 39 40 ' write XML representation of DataSet when button clicked41 Private Sub cmdWrite_Click(ByVal sender As System.Object, _42 ByVal e As System.EventArgs) Handles cmdWrite.Click43 44 ' write XML representation of DataSet to file45 BaseballDataSet.WriteXml("Players.xml")46 47 ' display XML in TextBox48 txtOutput.Text &= "Writing the following XML:" & _49 vbCrLf & BaseballDataSet.GetXml() & vbCrLf50 End Sub ' cmWrite_Click51 52 End Class ' FrmXMLWriter

DataSet method WriteXml is invoked to generate an XML representation of the data contained in the DataSet and then writes the XML to the specified file


77

19.8 Reading and Writing XML Documents

1 <?xml version="1.0" standalone="yes"?>2 <NewDataSet>3 <Players>4 <firstName>John</firstName>5 <lastName>Doe</lastName>6 <battingAverage>0.375</battingAverage>7 <playerID>1</playerID>8 </Players>9 10 <Players>11 <firstName>Jack</firstName>12 <lastName>Smith</lastName>13 <battingAverage>0.223</battingAverage>14 <playerID>2</playerID>15 </Players>16 17 <Players>18 <firstName>George</firstName>19 <lastName>O'Malley</lastName>20 <battingAverage>0.444</battingAverage>21 <playerID>3</playerID>22 </Players>23 </NewDataSet>

Fig. 19.31 XML document generated from DataSet in DatabaseXMLWriter.