The document outlines how to connect to and query an Access database using ADO.NET in C#. It describes creating a TableDisplay form with a DataGrid to display query results. The form initializes a DataSet and OleDbDataAdapter to retrieve data from the Authors table and bind it to the DataGrid. It also configures OleDbCommands for selecting, inserting, updating, and deleting data.

1. Chapter 19 – Database, SQL, and ADO .NET Outline 19.1 Introduction 19.2 Relational Database Model 19.3 Relational Database Overview: Books Database 19.4 Structured Query Language (SQL) 19.4.1 Basic SELECT Query 19.4.2 WHERE Clause 19.4.3 ORDER BY Clause 19.4.4 Merging Data from Multiple Tables: INNER JOIN 19.4.5 Joining Data from Tables Authors, AuthorISBN, Titles and Publishers 19.4.6 INSERT Statement 19.4.7 UPDATE Statement 19.4.8 DELETE Statement

2. Chapter 19 – Database, SQL, and ADO .NET Outline 19.5 ADO .NET Object Model 19.6 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 Database 19.7 Programming with ADO.NET: Modifying a DBMS 19.8 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/column primary 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. 19.3 Relational Database Overview: Books Database 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. 19.3 Relational Database Overview: Books Database

9. 19.3 Relational Database Overview: Books Database

10. 19.3 Relational Database Overview: Books Database

11. 19.3 Relational Database Overview: Books Database

12. 19.3 Relational Database Overview: Books Database

13. 19.3 Relational Database Overview: Books Database Fig. 19.10 part 1

14. 19.3 Relational Database Overview: Books Database Fig. 19.10 part 2

15. 19.3 Relational Database Overview: Books Database Fig. 19.10 part 3

16. 19.3 Relational Database Overview: Books Database Fig. 19.11 Table relationships in Books . AuthorISBN authorID isbn Authors authorID firstName lastName Publishers publisherID publisherName Titles isbn title editionNumber copyright publisherID imageFile price 1    1 1

17. 19.4 Structured Query Language (SQL) Used to request data (perform queries) and manipulate data

18. 19.4 Structured Query Language (SQL)

19. 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 *

20. 19.4.1 Basic Select Query

21. 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

22. 19.4.2 WHERE Clause

23. 19.4.2 WHERE Clause

24. 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

25. 19.4.3 ORDER BY Clause

26. 19.4.3 ORDER BY Clause

27. 19.4.3 ORDER BY Clause

28. 19.4.3 ORDER BY Clause

29. 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

30. 19.4.4 Merging Data from Multiple Tables: INNER JOIN

31. 19.4.5 Joining Data from Tables Authors, AuthorISBN, Titles and Publishers Tables produced by INNER JOIN can be used as arguments for another INNER JOIN

32. 19.4.5 Joining Data from Tables Authors , AuthorISBN , Titles and Publishers 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

33. 19.4.5 Joining Data from Tables Authors , AuthorISBN , Titles and Publishers Fig. 19.23 part 1

34. 19.4.5 Joining Data from Tables Authors , AuthorISBN , Titles and Publishers Fig. 19.23 part 2

35. 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

36. 19.4.6 INSERT Statement

37. 19.4.7 UPDATE Statement Modifies data in a table Form: UPDATE tableName SET fieldName1 = value1 WHERE criteria

38. 19.4.7 UPDATE Statement

39. 19.4.8 DELETE Statement Removes data from a table Form: DELETE FROM tableName WHERE criteria

40. 19.4.8 DELETE Statement

41. 19.5 ADO .NET and Object Model Provides an API for accessing database systems programmatically DataSets act as caches: Store data from source in local memory

42. 19.6 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 query

43. 19.6.1 Connecting to and Querying an Access Data Source Retrieves data and stores it in a DataGrid

44. TableDisplay.cs 1 // Fig. 19.27: TableDisplay.cs 2 // Displays data from a database table. 3 4 using System; 5 using System.Drawing; 6 using System.Collections; 7 using System.ComponentModel; 8 using System.Windows.Forms; 9 using System.Data; 10 11 // Summary description for TableDisplay.cs. 12 public class TableDisplay : System.Windows.Forms.Form 13 { 14 private System.Data.DataSet dataSet1; 15 private System.Data.OleDb.OleDbDataAdapter oleDbDataAdapter1; 16 private System.Windows.Forms.DataGrid dataGrid1; 17 private System.Data.OleDb.OleDbCommand oleDbSelectCommand1; 18 private System.Data.OleDb.OleDbCommand oleDbInsertCommand1; 19 private System.Data.OleDb.OleDbCommand oleDbUpdateCommand1; 20 private System.Data.OleDb.OleDbCommand oleDbDeleteCommand1; 21 private System.Data.OleDb.OleDbConnection oleDbConnection1; 22 23 private System.ComponentModel.Container components = null ; 24 25 public TableDisplay() 26 { 27 InitializeComponent(); 28 29 // Fill dataSet1 with data 30 oleDbDataAdapter1.Fill( dataSet1, "Authors" ); 31 32 // bind data in Users table in dataSet1 to dataGrid1 33 dataGrid1.SetDataBinding( dataSet1, "Authors" ); 34 } 35 Constructor to populate dataSet1 Call method fill to retrieve data from database associated with oleDbConnection Bind DataGrid to data source

45. TableDisplay.cs 36 private void InitializeComponent() 37 { 38 this .dataSet1 = new System.Data.DataSet(); 39 this .oleDbDataAdapter1 = 40 new System.Data.OleDb.OleDbDataAdapter(); 41 this .dataGrid1 = new System.Windows.Forms.DataGrid(); 42 this .oleDbSelectCommand1 = 43 new System.Data.OleDb.OleDbCommand(); 44 this .oleDbInsertCommand1 = 45 new System.Data.OleDb.OleDbCommand(); 46 this .oleDbUpdateCommand1 = 47 new System.Data.OleDb.OleDbCommand(); 48 this .oleDbDeleteCommand1 = 49 new System.Data.OleDb.OleDbCommand(); 50 this .oleDbConnection1 = 51 new System.Data.OleDb.OleDbConnection(); 52 ((System.ComponentModel.ISupportInitialize) 53 ( this .dataSet1)).BeginInit(); 54 ((System.ComponentModel.ISupportInitialize) 55 ( this .dataGrid1)).BeginInit(); 56 this .SuspendLayout(); 57 // 58 // dataSet1 59 // 60 this .dataSet1.DataSetName = "NewDataSet" ; 61 this .dataSet1.Locale = 62 new System.Globalization.CultureInfo( "en-US" ); 63 // 64 // oleDbDataAdapter1 65 // 66 this .oleDbDataAdapter1.DeleteCommand = 67 this .oleDbDeleteCommand1; 68 this .oleDbDataAdapter1.InsertCommand = 69 this .oleDbInsertCommand1; Specify how oleDbDataAdapter deletes data Specify how oleDbDataAdapter inserts data

46. TableDisplay.cs 70 this .oleDbDataAdapter1.SelectCommand = 71 this .oleDbSelectCommand1; 72 this .oleDbDataAdapter1.TableMappings.AddRange( 73 new System.Data.Common.DataTableMapping[] { 74 new System.Data.Common.DataTableMapping( 75 "Table" , "Authors" , 76 new System.Data.Common.DataColumnMapping[] { 77 new System.Data.Common.DataColumnMapping( 78 "authorID" , "authorID" ), 79 new System.Data.Common.DataColumnMapping( 80 "firstName" , "firstName"), 81 new System.Data.Common.DataColumnMapping( 82 "lastName" , "lastName" )})}); 83 this .oleDbDataAdapter1.UpdateCommand = 84 this .oleDbUpdateCommand1; 85 // 86 // dataGrid1 87 // 88 this .dataGrid1.DataMember = "" ; 89 this .dataGrid1.HeaderForeColor = 90 System.Drawing.SystemColors.ControlText; 91 this .dataGrid1.Location = 92 new System.Drawing.Point( 16 , 16 ); 93 this .dataGrid1.Name = "dataGrid1" ; 94 this .dataGrid1.Size = new System.Drawing.Size( 264 , 248 ); 95 this .dataGrid1.TabIndex = 0 ; 96 // 97 // oleDbSelectCommand1 98 // 99 this .oleDbSelectCommand1.CommandText = 100 "SELECT authorID, firstName, lastName FROM Authors" ; 101 this .oleDbSelectCommand1.Connection = 102 this .oleDbConnection1; Specify how oleDbDataAdapter selects data Specify how oleDbDataAdapter updates data

47. TableDisplay.cs 103 // 104 // oleDbInsertCommand1 105 // 106 this .oleDbInsertCommand1.CommandText = 107 "INSERT INTO Authors(firstName, lastName) VALUES " + 108 "(?, ?)" ; 109 this .oleDbInsertCommand1.Connection = 110 this .oleDbConnection1; 111 this .oleDbInsertCommand1.Parameters.Add( 112 new System.Data.OleDb.OleDbParameter( "firstName" , 113 System.Data.OleDb.OleDbType.VarWChar, 50 , 114 "firstName" )); 115 this .oleDbInsertCommand1.Parameters.Add( 116 new System.Data.OleDb.OleDbParameter( "lastName" , 117 System.Data.OleDb.OleDbType.VarWChar, 50 , 118 "lastName" )); 119 // 120 // oleDbUpdateCommand1 121 // 122 this .oleDbUpdateCommand1.CommandText = 123 "UPDATE Authors SET firstName = ?, lastName = ? WHERE" + 124 " (authorID = ?) AND (firstNam" + 125 "e = ? OR ? IS NULL AND firstName IS NULL) AND " + 126 "(lastName = ? OR ? IS NULL AND las" + 127 "tName IS NULL)" ; 128 this .oleDbUpdateCommand1.Connection = 129 this .oleDbConnection1; 130 this .oleDbUpdateCommand1.Parameters.Add( 131 new System.Data.OleDb.OleDbParameter( 132 "firstName" , 133 System.Data.OleDb.OleDbType.VarWChar, 134 50 , "firstName" )); 135 this .oleDbUpdateCommand1.Parameters.Add( 136 new System.Data.OleDb.OleDbParameter( 137 "lastName" , Set connection property for oleDbUpdageCommand1 Set CommandText for oleDbUpdageCommand1

48. TableDisplay.cs 138 System.Data.OleDb.OleDbType.VarWChar, 50 , 139 "lastName" )); 140 this .oleDbUpdateCommand1.Parameters.Add( 141 new System.Data.OleDb.OleDbParameter( 142 "Original_authorID" , 143 System.Data.OleDb.OleDbType.Integer, 0 , 144 System.Data.ParameterDirection.Input, false , 145 ((System. Byte )( 10 )), ((System. Byte )( 0 )), 146 "authorID" , System.Data.DataRowVersion.Original, 147 null )); 148 this .oleDbUpdateCommand1.Parameters.Add( 149 new System.Data.OleDb.OleDbParameter( 150 "Original_firstName" , 151 System.Data.OleDb.OleDbType.VarWChar, 50 , 152 System.Data.ParameterDirection.Input, false , 153 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 154 "firstName" , System.Data.DataRowVersion. Original , 155 null )); 156 this .oleDbUpdateCommand1.Parameters.Add( 157 new System.Data.OleDb.OleDbParameter( 158 "Original_firstName1" , 159 System.Data.OleDb.OleDbType.VarWChar, 50 , 160 System.Data.ParameterDirection.Input, false , 161 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 162 "firstName" , System.Data.DataRowVersion. Original , 163 null )); 164 this .oleDbUpdateCommand1.Parameters.Add( 165 new System.Data.OleDb.OleDbParameter( 166 "Original_lastName" , 167 System.Data.OleDb.OleDbType.VarWChar, 50 , 168 System.Data.ParameterDirection.Input, false , 169 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 170 "lastName" , System.Data.DataRowVersion. Original , 171 null ));

49. TableDisplay.cs 172 this .oleDbUpdateCommand1.Parameters.Add( 173 new System.Data.OleDb.OleDbParameter( 174 "Original_lastName1" , 175 System.Data.OleDb.OleDbType.VarWChar, 50 , 176 System.Data.ParameterDirection.Input, false , 177 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 178 "lastName" , System.Data.DataRowVersion. Original , 179 null )); 180 // 181 // oleDbDeleteCommand1 182 // 183 this .oleDbDeleteCommand1.CommandText = 184 "DELETE FROM Authors WHERE (authorID = ?) AND " + 185 "(firstName = ? OR ? IS NULL AND firs" + 186 "tName IS NULL) AND (lastName = ? OR ? IS NULL AND " + 187 "lastName IS NULL)" ; 188 this .oleDbDeleteCommand1.Connection = 189 this .oleDbConnection1; 190 this .oleDbDeleteCommand1.Parameters.Add( 191 new System.Data.OleDb.OleDbParameter( 192 "Original_authorID" , 193 System.Data.OleDb.OleDbType. Integer , 0 , 194 System.Data.ParameterDirection.Input, false , 195 ((System. Byte )( 10 )), ((System. Byte )( 0 )), 196 "authorID" , System.Data.DataRowVersion. Original , 197 null )); 198 this .oleDbDeleteCommand1.Parameters.Add( 199 new System.Data.OleDb.OleDbParameter( 200 "Original_firstName" , 201 System.Data.OleDb.OleDbType.VarWChar, 50 , 202 System.Data.ParameterDirection.Input, false , 203 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 204 "firstName" , System.Data.DataRowVersion. Original , 205 null ));

50. TableDisplay.cs 206 this .oleDbDeleteCommand1.Parameters.Add( 207 new System.Data.OleDb.OleDbParameter( 208 "Original_firstName1" , 209 System.Data.OleDb.OleDbType.VarWChar, 50 , 210 System.Data.ParameterDirection.Input, false , 211 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 212 "firstName" , System.Data.DataRowVersion. Original , 213 null )); 214 this .oleDbDeleteCommand1.Parameters.Add( 215 new System.Data.OleDb.OleDbParameter( 216 "Original_lastName" , 217 System.Data.OleDb.OleDbType.VarWChar, 50 , 218 System.Data.ParameterDirection.Input, false , 219 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 220 "lastName" , System.Data.DataRowVersion. Original , 221 null )); 222 this .oleDbDeleteCommand1.Parameters.Add( 223 new System.Data.OleDb.OleDbParameter( 224 "Original_lastName1" , 225 System.Data.OleDb.OleDbType.VarWChar, 50 , 226 System.Data.ParameterDirection.Input, false , 227 ((System. Byte )( 0 )), ((System. Byte )( 0 )), 228 "lastName" , System.Data.DataRowVersion. Original , 229 null )); 230 // 231 // oleDbConnection1 232 //

51. TableDisplay.cs 233 this .oleDbConnection1.ConnectionString = 234 @"Provider=Microsoft.Jet.OLEDB.4.0;Password="""";" + 235 @"User ID=Admin;Data Source=C:\Books\2001\csphtp1\" + 236 @"csphtp1_examples\ch19\Books.mdb;Mode=Share " + 237 @"Deny None;Extended Properties="""";Jet OLEDB:" + 238 @"System database="""";Jet OLEDB:Registry " + 239 @"Path="""";Jet OLEDB:Database Password="""";" + 240 @"Jet OLEDB:Engine Type=5;Jet OLEDB:Database " + 241 @"Locking Mode=1;Jet OLEDB:Global Partial Bulk " + 242 @"Ops=2;Jet OLEDB:Global Bulk Transactions=1;Jet " + 243 @"OLEDB:New Database Password="""";Jet OLEDB:" + 244 @"Create System Database=False;Jet OLEDB:Encrypt " + 245 @"Database=False;Jet OLEDB:Don't Copy Locale on " + 246 @"Compact=False;Jet OLEDB:Compact Without Replica " + 247 @"Repair=False;Jet OLEDB:SFP=False" ; 248 // 249 // TableDisplay 250 // 251 this .AutoScaleBaseSize = new System.Drawing.Size( 5 , 13 ); 252 this .ClientSize = new System.Drawing.Size( 292 , 273 ); 253 this .Controls.AddRange( 254 new System.Windows.Forms.Control[] { 255 this .dataGrid1}); 256 this .Name = "TableDisplay" ; 257 this .Text = "TableDisplay" ; 258 ((System.ComponentModel.ISupportInitialize) 259 ( this .dataSet1)).EndInit(); 260 ((System.ComponentModel.ISupportInitialize) 261 ( this .dataGrid1)).EndInit(); 262 this .ResumeLayout( false ); 263 Initialize oleDbConnection, and specify path to database

52. TableDisplay.cs Program Output 264 } // end of InitializeComponent 265 266 [STAThread] 267 static void Main() 268 { 269 Application.Run( new TableDisplay() ); 270 } 271 }

53. 19.6.2 Querying the Books Database Use SELECT statements on database and display results

54. DisplayQueryResults.cs 1 // Fig. 19.28: DisplayQueryResults.cs 2 // Displays the contents of the authors database. 3 4 using System; 5 using System.Drawing; 6 using System.Collections; 7 using System.ComponentModel; 8 using System.Windows.Forms; 9 using System.Data; 10 11 public class DisplayQueryResults : System.Windows.Forms.Form 12 { 13 private System.Data.OleDb.OleDbConnection oleDbConnection1; 14 private System.Data.DataSet dataSet1; 15 private System.Data.OleDb.OleDbDataAdapter oleDbDataAdapter1; 16 private System.Data.OleDb.OleDbCommand oleDbSelectCommand1; 17 private System.Data.OleDb.OleDbCommand oleDbInsertCommand1; 18 private System.Data.OleDb.OleDbCommand oleDbUpdateCommand1; 19 private System.Data.OleDb.OleDbCommand oleDbDeleteCommand1; 20 private System.Windows.Forms.TextBox queryTextBox; 21 private System.Windows.Forms.Button submitButton; 22 private System.Windows.Forms.DataGrid dataGrid1; 23 private System.ComponentModel.Container components = null ; 24 25 public DisplayQueryResults() 26 { 27 28 InitializeComponent(); 29 } 30 31 // Visual Studio.NET generated code 32

55. DisplayQueryResults.cs 33 [STAThread] 34 static void Main() 35 { 36 Application.Run( new DisplayQueryResults() ); 37 } 38 39 // perform SQL query on data 40 private void submitButton_Click( object sender, 41 System.EventArgs e ) 42 { 43 try 44 { 45 // set SQL query to what user 46 // input into queryTextBox 47 oleDbDataAdapter1.SelectCommand.CommandText = 48 queryTextBox.Text; 49 50 // clear DataSet from previous operation 51 dataSet1.Clear(); 52 53 // Fill data set with information that results 54 // from SQL query 55 oleDbDataAdapter1.Fill( dataSet1, "Authors" ); 56 57 // bind DataGrid to contents of DataSet 58 dataGrid1.SetDataBinding( dataSet1, "Authors" ); 59 } 60 61 catch ( System.Data.OleDb.OleDbException oleException ) 62 { 63 MessageBox.Show( "Invalid query" ); 64 } 65 66 } // end of submitButton_Click 67 } When user clicks submit button, assign SELECT query string to OleDbDataAdapter’s SelectCommand property Place data from database into dataSet1 Bind DataGrid to data and display results

56. DisplayQueryResults.cs Program Output

57. 19.7 Programming with ADO.NET: Modifying a DBMS Example implements an address book User can insert, locate and update records

58. AddressBook.cs 1 // Fig. 19.29: AddressBook.cs 2 // Using SQL statements to manipulate a database. 3 4 using System; 5 using System.Drawing; 6 using System.Collections; 7 using System.ComponentModel; 8 using System.Windows.Forms; 9 using System.Data; 10 11 public class AddressBook : System.Windows.Forms.Form 12 { 13 private System.Windows.Forms.TextBox faxTextBox; 14 private System.Windows.Forms.TextBox homeTextBox; 15 private System.Windows.Forms.TextBox firstTextBox; 16 private System.Windows.Forms.TextBox stateTextBox; 17 private System.Windows.Forms.TextBox idTextBox; 18 private System.Windows.Forms.TextBox lastTextBox; 19 private System.Windows.Forms.TextBox postalTextBox; 20 private System.Windows.Forms.TextBox addressTextBox; 21 private System.Windows.Forms.TextBox cityTextBox; 22 private System.Windows.Forms.TextBox countryTextBox; 23 private System.Windows.Forms.TextBox emailTextBox; 24 private System.Data.DataSet dataSet1; 25 private System.Data.OleDb.OleDbDataAdapter oleDbDataAdapter1; 26 private System.Data.OleDb.OleDbCommand oleDbSelectCommand1; 27 private System.Data.OleDb.OleDbCommand oleDbInsertCommand1; 28 private System.Data.OleDb.OleDbCommand oleDbUpdateCommand1; 29 private System.Data.OleDb.OleDbCommand oleDbDeleteCommand1; 30 private System.Data.OleDb.OleDbConnection oleDbConnection1; 31 private System.Windows.Forms.TextBox statusTextBox; 32 private System.Windows.Forms.Label addressLabel; 33 private System.Windows.Forms.Label cityLabel; 34 private System.Windows.Forms.Label stateLabel; 35 private System.Windows.Forms.Label idLabel;

59. AddressBook.cs 36 private System.Windows.Forms.Label firstLabel; 37 private System.Windows.Forms.Label lastLabel; 38 private System.Windows.Forms.Label postalLabel; 39 private System.Windows.Forms.Label countryLabel; 40 private System.Windows.Forms.Label emailLabel; 41 private System.Windows.Forms.Button clearButton; 42 private System.Windows.Forms.Button helpButton; 43 private System.Windows.Forms.Button findButton; 44 private System.Windows.Forms.Button addButton; 45 private System.Windows.Forms.Button updateButton; 46 private System.Windows.Forms.Label faxLabel; 47 private System.Windows.Forms.Label homeLabel; 48 private System.ComponentModel.Container components = null ; 49 50 public AddressBook() 51 { 52 InitializeComponent(); 53 oleDbConnection1.Open(); 54 } 55 56 // Visual Studio.NET generated code 57 58 [STAThread] 59 static void Main() 60 { 61 Application.Run( new AddressBook() ); 62 } 63 64 private void findButton_Click( object sender, 65 System.EventArgs e ) 66 { 67 try 68 { Perform SELECT query on database

60. AddressBook.cs 69 if ( lastTextBox.Text != "" ) 70 { 71 // clear DataSet from last operation 72 dataSet1.Clear(); 73 74 // create SQL query to find contact with 75 // specified last name 76 oleDbDataAdapter1.SelectCommand.CommandText = 77 "SELECT * FROM addresses WHERE lastname = '" + 78 lastTextBox.Text + "'" ; 79 80 // fill dataSet1 with rows resulting from 81 // query 82 oleDbDataAdapter1.Fill( dataSet1 ); 83 84 // display information 85 Display( dataSet1 ); 86 statusTextBox.Text += "\r\nQuery successful\r\n" ; 87 } 88 else 89 lastTextBox.Text = 90 "Enter last name here then press Find" ; 91 } 92 93 catch ( System.Data.OleDb.OleDbException oleException ) 94 { 95 Console.WriteLine( oleException.StackTrace ); 96 statusTextBox.Text += oleException.ToString(); 97 } 98 Empty DataSet of prior data Modify SQL query’s text to perform SELECT operation Fill DataSet with query results Display data in textboxes

61. AddressBook.cs 99 catch ( InvalidOperationException invalidException ) 100 { 101 MessageBox.Show( invalidException.Message ); 102 } 103 104 } // end of findButton_Click 105 106 private void addButton_Click( object sender, System.EventArgs e ) 107 { 108 try 109 { 110 if ( lastTextBox.Text != "" && firstTextBox.Text != "" ) 111 { 112 // create SQL query to insert row 113 oleDbDataAdapter1.InsertCommand.CommandText = 114 "INSERT INTO addresses (" + 115 "firstname, lastname, address, city, " + 116 "stateorprovince, postalcode, country, " + 117 "emailaddress, homephone, faxnumber" + 118 ") VALUES ('" + 119 firstTextBox.Text + "', '" + 120 lastTextBox.Text + "', '" + 121 addressTextBox.Text + "', '" + 122 cityTextBox.Text + "', '" + 123 stateTextBox.Text + "', '" + 124 postalTextBox.Text + "', '" + 125 countryTextBox.Text + "', '" + 126 emailTextBox.Text + "', '" + 127 homeTextBox.Text + "', '" + 128 faxTextBox.Text + "')" ; 129 130 // notify user that query is being sent 131 statusTextBox.Text += "\r\nSending query: " + 132 oleDbDataAdapter1.InsertCommand.CommandText + 133 "\r\n" ; Perform INSERT operation using OleDbCommand members Sets CommandText property of InsertCommand to execute proper INSERT statement

62. AddressBook.cs 134 135 // send query 136 oleDbDataAdapter1.InsertCommand.ExecuteNonQuery(); 137 138 statusTextBox.Text += "\r\nQuery successful\r\n" ; 139 } 140 else 141 statusTextBox.Text += "\r\nEnter at least first " + 142 "and last name then press Add\r\n" ; 143 } 144 145 catch ( System.Data.OleDb.OleDbException oleException ) 146 { 147 Console.WriteLine( oleException.StackTrace ); 148 statusTextBox.Text += oleException.ToString(); 149 } 150 151 } // end of addButton_Click 152 153 private void updateButton_Click( object sender, 154 System.EventArgs e ) 155 { 156 try 157 { 158 // make sure users have found record 159 // they wish to update 160 if ( idTextBox.Text != "" ) 161 { 162 // set SQL query to update all fields in 163 // table where id number matches id 164 // in idTextBox 165 oleDbDataAdapter1.UpdateCommand.CommandText = 166 "UPDATE addresses SET " + 167 "firstname ='" + firstTextBox.Text + 168 "', lastname='" + lastTextBox.Text + Perform UPDATE operation using OleDbCommand members Send inset query to perform INSERT operation Sets CommandText property of UpdateCommand to execute proper Update statement

63. AddressBook.cs 169 "', address='" + addressTextBox.Text + 170 "', city='" + cityTextBox.Text + 171 "', stateorprovince='" + stateTextBox.Text + 172 "', postalcode='" + postalTextBox.Text + 173 "', country='" + countryTextBox.Text + 174 "', emailaddress='" + emailTextBox.Text + 175 "', homephone='" + homeTextBox.Text + 176 "', faxnumber='" + faxTextBox.Text + 177 "' WHERE id=" + idTextBox.Text; 178 179 // notify user that query is being set 180 statusTextBox.Text += "\r\nSending query: " + 181 oleDbDataAdapter1.UpdateCommand.CommandText + 182 "\r\n" ; 183 184 // execute query 185 oleDbDataAdapter1.UpdateCommand.ExecuteNonQuery(); 186 187 statusTextBox.Text += "\r\nQuery successful\r\n" ; 188 } 189 else 190 statusTextBox.Text += "\r\nYou may only update " + 191 "an existing record. Use Find to locate the" + 192 "record, then modify the information and " + 193 "press Update.\r\n" ; 194 } 195 196 catch ( System.Data.OleDb.OleDbException oleException ) 197 { 198 Console.WriteLine( oleException.StackTrace ); 199 statusTextBox.Text += oleException.ToString(); 200 } 201 202 } // end of updateButton_Click 203 Send update query to perform UPDATE operation

64. AddressBook.cs 204 private void clearButton_Click( object sender, 205 System.EventArgs e ) 206 { 207 idTextBox.Clear(); 208 ClearTextBoxes(); 209 } 210 211 private void helpButton_Click( object sender, 212 System.EventArgs e ) 213 { 214 statusTextBox.AppendText( 215 "\r\nClick Find to locate a record\r\n" + 216 "Click Add to insert a new record.\r\n" + 217 "Click Update to update the information in a record " 218 + "\r\nClick Clear to empty the textboxes" ); 219 } 220 221 private void Display( DataSet dataSet ) 222 { 223 try 224 { 225 // get first DataTable--there always will be one 226 DataTable dataTable = dataSet.Tables[ 0 ]; 227 228 if ( dataTable.Rows.Count != 0 ) 229 { 230 int recordNumber = ( int ) dataTable.Rows[ 0 ][ 0 ]; 231 232 idTextBox.Text = recordNumber.ToString(); 233 firstTextBox.Text = 234 ( string ) dataTable.Rows[ 0 ][ 1 ]; 235 lastTextBox.Text = 236 ( string ) dataTable.Rows[ 0 ][ 2 ]; 237 addressTextBox.Text = 238 ( string ) dataTable.Rows[ 0 ][ 3 ]; Updates display with data acquired by query DataTable from DataSet, contains results of query Determine if query returned any rows Retrieve first field of database Retrieve the rest of the fields of database Display instructions if user clicks help Clear textboxes if user clicks clear

65. AddressBook.cs 239 cityTextBox.Text = 240 ( string ) dataTable.Rows[ 0 ][ 4 ]; 241 stateTextBox.Text = 242 ( string ) dataTable.Rows[ 0 ][ 5 ]; 243 postalTextBox.Text = 244 ( string ) dataTable.Rows[ 0 ][ 6 ]; 245 countryTextBox.Text = 246 ( string ) dataTable.Rows[ 0 ][ 7 ]; 247 emailTextBox.Text = 248 ( string ) dataTable.Rows[ 0 ][ 8 ]; 249 homeTextBox.Text = 250 ( string ) dataTable.Rows[ 0 ][ 9 ]; 251 faxTextBox.Text = 252 ( string ) dataTable.Rows[ 0 ][ 10 ]; 253 } 254 255 else 256 statusTextBox.Text += "\r\nNo record found\r\n "; 257 } 258 259 catch ( System.Data.OleDb.OleDbException oleException ) 260 { 261 Console.WriteLine( oleException.StackTrace ); 262 statusTextBox.Text += oleException.ToString(); 263 } 264 265 } // end Display 266 267 private void ClearTextBoxes() 268 { 269 firstTextBox.Clear(); 270 lastTextBox.Clear(); 271 addressTextBox.Clear(); 272 cityTextBox.Clear(); 273 stateTextBox.Clear();

66. AddressBook.cs Program Output 274 postalTextBox.Clear(); 275 countryTextBox.Clear(); 276 emailTextBox.Clear(); 277 homeTextBox.Clear(); 278 faxTextBox.Clear(); 279 } 280 }

67. AddressBook.cs Program Output

68. AddressBook.cs Program Output

69. AddressBook.cs Program Output

70. 19.8 Reading and Writing XML Files ADO.NET can convert data from data source into XML files Uses methods WriteXml, ReadXml andGetXml

71. XMLWriter.cs 1 // Fig. 19.30 XMLWriter.cs 2 // Demonstrates generating XML from an ADO .NET DataSet. 3 4 using System; 5 using System.Drawing; 6 using System.Collections; 7 using System.ComponentModel; 8 using System.Windows.Forms; 9 using System.Data; 10 11 public class DatabaseXMLWriter : System.Windows.Forms.Form 12 { 13 private System.Data.OleDb.OleDbConnection baseballConnection; 14 private System.Data.OleDb.OleDbDataAdapter playersDataAdapter; 15 private System.Data.OleDb.OleDbCommand oleDbSelectCommand1; 16 private System.Data.OleDb.OleDbCommand oleDbInsertCommand1; 17 private System.Data.OleDb.OleDbCommand oleDbUpdateCommand1; 18 private System.Data.OleDb.OleDbCommand oleDbDeleteCommand1; 19 private System.Data.DataSet playersDataSet; 20 private System.Windows.Forms.DataGrid playersDataGrid; 21 private System.Windows.Forms.Button writeButton; 22 private System.Windows.Forms.TextBox outputTextBox; 23 private System.ComponentModel.Container components = null ; 24 25 public DatabaseXMLWriter() 26 { 27 // 28 // Required for Windows Form Designer support 29 // 30 InitializeComponent(); 31 32 // open database connection 33 baseballConnection.Open(); 34 Create connection to database

72. XMLWriter.cs 35 // fill DataSet with data from OleDbDataAdapter 36 playersDataAdapter.Fill( playersDataSet, "Players" ); 37 38 // bind DataGrid to DataSet 39 playersDataGrid.SetDataBinding( playersDataSet, "Players" ); 40 41 } 42 43 // Visual Studio .NET generated code 44 45 // main entry point for application. 46 [STAThread] 47 static void Main() 48 { 49 Application.Run( new DatabaseXMLWriter() ); 50 } 51 52 // write XML representation of DataSet when button is clicked 53 private void writeButton_Click( 54 object sender, System.EventArgs e) 55 { 56 // write XML representation of DataSet to file 57 playersDataSet.WriteXml( "Players.xml" ); 58 59 // display XML in TextBox 60 outputTextBox.Text += "Writing the following XML:\n\n" + 61 playersDataSet.GetXml() + "\n\n" ; 62 63 } 64 } Populate playersDataSet with data from database Bind DataGrid to DataSet to display data Create XML representation of data when user clicks button Append XML representation to textbox

73. XMLWriter.cs

74. 19.8 Reading and Writing XML Documents Fig. 19.31 XML document generated from DataSet in DatabaseXMLWriter .