Database: Integrated collection of data

Transcription

1 CSC 330 Object Oriented Programming C# and Databases

2 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 2

3 What are Databases? Features of Database management system (DBMS) Definition of data structure Maintenance facility Allow access to and storage of data independently of the internal representation of data Main job of the DBMS is to ensure data integrity 3

4 Relational Database Systems and SQL Relational database systems are the most popular today (Microsoft Access is a relational database system) SQL is international standard language used with relational database systems to perform queries (i.e. to request information that satisfies given criteria) and to manipulate data Some popular relational database management systems (RDBMS) are Microsoft SQL Server, Oracle, MySQL, Sybase 4

5 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

6 Relational Database Model All information is contained in tables (or relations) Tuple or row (record) Attribute or column (field) Relationships [not why called relational] 6

7 Relation Instance The current values (relation instance) of a relation are specified by a table An element t of r is a tuple, represented by a row in a table customer_name customer_street customer_city attributes (or columns) Jones Smith Curry Main North North P k Harrison Rye Rye Pitt fi ld Lindsay Park Pittsfield tuples (or rows) customer 7

8 Relational Database Model Relationships are logical representation of data: Not concerned with physical structure Primary key: field that contains unique data Each record can be identified by at least one distinct value record/row number name department salary location Jones New Jersey Kerwin New Jersey Larson Los Angeles Myers Orlando Neumann New Jersey Stephens Orlando primary key field/column 8

9 Primary Keys Relational l DBMS enforces several constraints t on data Rule of Entity Integrity: every record must have a unique value in its primary-key field Primary key does not have to be a single field Compound Primary Key: when a record has a unique key based on a combination of two fields 9

10 Foreign Keys A foreign key is used to create relationships: 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 10

11 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 11

12 Relational Database Overview: Books Database Field Descrip tion authorid firstname lastname Fig Author s ID number in the database. In the Books database, this int field is defined as an auto-incremented field. For each new record inserted in this table, the database increments the authorid value, ensuring that each record has a unique authorid. This field represents the table s primary key. Author s first name (a string). Author s last name (a string). Authors table from Books. 12

13 Relational Database Overview: Books Database 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 13 Jeffrey Listfield Fig Data from the Authors table of Books. 13

14 Relational Database Overview: Books Database Field publisherid Description The publisher s ID number in the database. This auto-incremented int field is the table s primary-key field. publishername The name of the publisher (a string). Fig Publishers table from Books. publisherid publishername 1 Prentice Hall 2 Prentice Hall PTG Fig Data from the Publishers table of Books. Fie ld authorid Desc rip tion 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 Fig The ISBN number for a book (a string). AuthorISBN table from Books. 14

15 Relational Database Overview: Books Database authorid isbn authorid isbn x x x Fig Data from AuthorISBN ta b le in Books. 15

16 Relational Database Overview: Books Database Fie ld isbn Desc rip tion ISBN number of the book (a string). title editionnumber copyright publisherid imagefile price Fig Title of the book (a string). Edition number of the book (a string). Copyright year of the book (an int). Publisher s ID number (an int). This value must correspond to an ID number in the Publishers table. Name of the file containing the book s cover image (a string). Suggested retail price of the book (a real number). [Note: The prices shown in this database are for example purposes only.] Titles table from Books. 16

17 Fig part 1 Relational Database Overview: Books Database isbn title edition- publish- copyright imagefile price Number erid Python H ow to Program python.jpg $ C# How to Program Java H ow to Program The Complete Java Training C ourse A dvanced Java 2 Platform H o w to Program Intern et and W orld W ide W eb How to Program V isual B asic.n ET H o w to P r o g r a m cshtp.jpg $ jhtp4.jpg $ javactc4.jpg $ advjhtp1.jpg $ iw3htp2.jpg $ vbnet.jpg $ The C om pl ete C c ppct c 3. j pg $ Training C ourse The Complete e- B usiness & e- C o m m e r c e Program m ing Training C ourse X The Complete Intern et & W orld W ide W eb Program m ing Training C ourse The Complete Perl Training C ourse ebecctc.jpg $ iw3ctc2.jpg $ perl.jpg $ The Comp lete x mlctc.jpg $ XM L Program m ing Training C ourse 17

18 Fig part 2 Relational Database Overview: Books Database C How to Program chtp3.jpg $ C++ How to P rogram X e-b usiness and e- C om m erce H ow to Program W ireless Internet an d M ob ile B usiness H ow to Program Perl How to Program XM L How to Program The Complete I nternet and W orld W id e W eb Program m ing Training Course Java H ow to Program (Java 2) The Complete Java 2 Training ing Course e-b usiness and e- C om m erce for M a n a g ers Internet and W orld W ide W eb How to Program G etting S tarted with Visual C++ 6 with an Introduction to M F C cpphtp3.jpg $ ebechtp1.jpg $ wireless.jpg $ perlhtp1.jpg $ xmlhtp1.jpg $ iw3ctc1.jpg $ jhtp3.jpg $ javactc3.jpg $ ebecm.jpg $ iw3htp1.jpg $ gsvc.jpg $

19 Fig part 3 Relational Database Overview: Books Database The Complete Visual Basic 6 Training Course vbctc1.jpg $ Visual B asic vbhtp 1. j pg $ How to Program Java M ultim edia Cyber Classroom Java How to Program The Complete C++ Training Course C++ How to Program javactc.jpg $ jhtp1.jpg $ cppctc2.jpg $ cpphtp2.jpg $ The C omplet e J ava j avact c 2. j pg $ Training Course The Complete Java Training Course (Java 1.1) javactc2.jpg $ Java How to jhtp2. jpg $ Program (Java 1.1) C++ How to Program cpphtp1.jpg $ C How to Program chtp2.jpg $ C H ow t o P rogram chtp.j p g $ Fig Da ta fro m the Titles table of Books. 19

20 The Books Database Entity-relationship diagram for the Book database Authors authorid firstname lastname AuthorISBN 1 authorid isbn 1 Publishers publisherid 1 Titles isbn title editionnumber copyright publisherid imagefile publishername price 20

21 Relational Database Queries Queries : return a new result set Based upon relational algebra Uses 3 operations to build a new relation (a result-set) Projection, selection, and join 21

22 What is SQL? Structured Query Language (SQL) Keywords and rules used to implement relational algebra operations 22

23 SQL Keywords SQL ke yw o rd SELECT Description Selects (retrieves) fields from one or more tables. FROM WHERE INNER JOIN GROUP BY ORDER BY INSERT UPDATE DELETE Fig SQL query keywords. Specifies tables from which to get fields or delete records. Required in every SELECT and DELETE statement. Specifies criteria that determine the rows to be retrieved. Joins records from multiple tables to produce a single set of records. Specifies criteria for grouping records. Specifies criteria for ordering records. Inserts data into a specified table. Updates data in a specified table. Deletes data from a specified table. 23

24 Basic Select Query Extracts information from one or more tables in a database Format: Basic: select * from table-name Example: select * from authors * means "extract all columns" To get a projection (specific columns), use a list: select firstname, lastname from authors Column, table names may be case sensitive SQL keywords should not be case sensitive 24

25 Basic Select Query authorid lastname authorid lastname 1 Deitel 8 McPhie 2 Deitel 9 Yaeger 3 Nieto 10 Zlatkina 4 Steinbuhler 12 Wiedermann 5 Santry 12 Liperi 6 Lin 13 Listfield 7 Sadhu Fig authorid and lastname from the Authors tab le. 25

26 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 26

27 Pattern-matching with Where Can use like clause for string pattern matching Uses wildcards %: zero or more characters take its place (*) _: exactly one character takes its place (?) Examples: Select * from authors where firstname like '_e%' Select * from authors where lastname like 'D%' 27

28 WHERE Clause Title editionnumber copyright In te rn e t a n d W o rld W id e W e b H o w to P ro g ra m Java H ow to Program The Comp lete Java T rain in g Course The Com plete e-business & e-com m erce Program m ing Training Course T h e C o m p le te In te rn e t & W o rld W id e W eb Program m ing Training Course The Complete Perl Training Course The C om pl ete XML P ro gram m i ng T rai n i ng C ourse C How to Program C++ How to Program The Com plete C++ Training Course e-business and e-com m erce How to Program I n t ernet and W orld W id e W e b H ow to P ro gram T h e C o m p le te In te rn e t a n d W o rld W id e W eb Program m ing Training Course Java H ow to P rogram (Java 2) The Complete Java 2 Training Course XML How to Program Perl How to Program Advanced Java 2 Platform H ow to Program e-business and e-com m erce for M anagers W ireless Internet and M obile B usiness H ow to Program C# How To Program Python How to Program V isual B asic.n ET H ow to Program Fig Title s w ith c o p yrig h ts a fte r 1999 fro m ta b le Titles. 28

29 WHERE Clause authorid firstname lastname 1 Harvey Deitel 2 Paul Deitel Fig Authors from the Authors table whose last names start t with D. authorid firstname lastname 3 Tem Nieto 6 Ted Lin 11 Ben Wiedermann 12 Jonathan Liperi 13 Jeffrey Listfield Fig Authors from table Authors whose last names contain i as the sec ond letter. 29

30 Sorting the Results SQL queries return their data in indeterminate order Same query may return rows in different order each time Use the order by clause to arrange results of a query Can be ascending (asc) or descending (desc) order Examples: select * from authors order by lastname desc select * from authors order by lastname, firstname asc 30

31 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 31

32 ORDER BY Clause authorid firstname lastname 2 Paul Deitel 1 Harvey Deitel 6 Ted Lin 12 Jonathan Liperi i 13 Jeffrey Listfield 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 Authors from table Authors in ascending order by lastname. 32

33 ORDER BY Clause 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 13 Jeffrey Listfield 12 Jonathan Liperi 6 Ted Lin 2 Paul Deitel 1 Harvey Deitel Fig Authors from table Authors in descending order by lastname. 33

34 ORDER BY Clause authorid firstname lastname 1 Harvey Deitel 2 Paul Deitel 6 Ted Lin 12 Jonathan Liperi 13 Jeffrey Listfield 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 Authors from table Authors in ascending order by lastname and by firstname. 34

35 ORDER BY Clause isbn title edition- copyright price Number Advanced Java 2 Platform How to Program $ C How to Program $ C How to Program $ C How to Program $ C# How To Program $ C++ How to Program $ C++ How to Program $ C++ How to Program $ X e-business and e-com m erce How to Program Internet and W orld W ide W eb How to Prog ram Internet and W orld W ide W eb How to Program $ $ $ Java How to Program $ Java How to Program $ Perl How to Program $ Python H ow to Program $ V isual B asic.n ET H ow to Program V isual B asic 6 H ow to Program $ $ W ireless Internet and M ob ile $ Business How to Program XML How to Program $69.95 Fig Books from table Titles whose titles end with How to Program in a sc e n d in g o rd e r b y title. 35

36 Merging g Data from Multiple Tables: 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 table 2 on table1.field = table2.field Example: select firstname, isbn from authors inner join authorisbn on authors.authorid = authorsisbn.authorid 36

37 Merging Data from Multiple Tables: INNER JOIN firstname lastname isbn firstname lastname isbn Harvey D eitel Harvey D eitel Harvey D eitel Harvey D eitel H arvey D e ite l H arvey D e ite l Harvey D eitel Paul D eitel Harvey D eitel Paul D eitel Harvey D eitel Paul D eitel Harvey D eitel Paul D eitel x Harvey D eitel x Paul D eitel Harvey D eitel Paul D eitel Harvey D eitel Paul D eitel Harvey D eitel Paul D eitel Harvey D eitel Paul D eitel Harvey D eitel Paul D eitel Harvey D eitel Tem Nieto Paul D eitel Tem Nieto Paul D eitel Tem Nieto Paul D eitel Tem Nieto Paul D eitel Tem Nieto Paul D eitel Tem Nieto Paul D eitel Tem Nieto x Paul D eitel Fig Authors from table Authors and ISBN num bers of the authors books, sorted in ascending order by lastname and firstname. 37

38 Joining Data from Tables Authors, AuthorISBN, Titles and Publishers Tables produced by INNER JOIN can be used as arguments for another INNER JOIN 38

39 Joining Data from Tables Authors, AuthorISBN, Titles and Publishers 1 SELECT Titles.title, Titles.isbn, Authors.firstName, 2 Authors.lastName, Titles.copyright, 3 Publishers.publisherName 4 FROM 5 ( Publishers INNER JOIN Titles 6 ON Publishers.publisherID = Titles.publisherID ) 7 INNER JOIN 8 ( Authors INNER JOIN AuthorISBN 9 ON Authors.authorID = AuthorISBN.authorID ) 10 ON Titles.isbn = AuthorISBN.isbn 11 ORDER BY Titles.title 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 Fig TitleAuthor query of Books database. 39

40 Fig part 1 Joining Data from Tables Authors, AuthorISBN, Titles and Publishers Title isbn first- Name last- Name copyright publisher- Name Advanced Java 2 Platform Paul D eitel 2002 Prentice H all How to Program Advanced Java 2 Platform How to Program Harvey D eitel 2002 Prentice H all Advanced Java 2 Platform How to Prog ram Sean Santry 2002 Prentice H all C How to Program Harvey D eitel 1992 Prentice H all C How to Program Paul D eitel 1992 Prentice H all C How to Program Harvey D eitel 1994 Prentice H all C How to Program Paul D eitel 1994 Prentice Hall C How to Program Harvey D eitel 2001 Prentice H all C How to Program Paul D eitel 2001 Prentice H all C# How To Program Tem Nieto 2002 Prentice H all C# How To Program Paul D eitel 2002 Prentice Hall C# How To Program Jeffrey Listfield 2002 Prentice H all C# How To Program Cheryl Yaeger 2002 Prentice H all C# How To Program Marina Zlatkina 2002 Prentice H all C# How To Program Harvey D eitel 2002 Prentice Hall C++ How to Program Paul D eitel 2001 Prentice H all 40

41 Fig part 2 Joining Data from Tables Authors, AuthorISBN, Titles and Publishers C++ How to Program Harvey Deitel 2001 Prentice Hall C++ How to Program Paul Deitel 1994 Prentice Hall C++ How to Program Harvey Deitel 1994 Prentice Hall C++ How to Program Harvey Deitel 1998 Prentice Hall C++ How to Program Paul Deitel 1998 Prentice Hall e-business and e-commerce Harvey Deitel 2000 Prentice Hall for Managers e-business and e-commerce for Managers Kate Steinbuhl er 2000 Prentice Hall e-business and e-commerce Paul Deitel 2000 Prentice Hall for Managers e-business and e-commerce How to Program e-business and e-commerce How to Program X Harvey Deitel 2001 Prentice Hall X Paul Deitel 2001 Prentice Hall e-business and e-commerce How to Program X Tem Nieto 2001 Prentice Hall Fig Portion of the result set produced by the query in Fig

42 The Selection Operation The selection operation is accomplished using where Basic form: select * from table-name where criteria Example: select * from titles where copyright > 1999 Make sure String criteria are inside single quotes Can use expected relational operators select * from authors where firstname > 'B' 42

43 Insert Statement Inserts a new record into a table General form: insert into table-name(fieldname1, fieldname2,...) values(value1, value2) Example: insert into authors(authorid, lastname, firstname) values(15, 'Gilbert', 'Steve') Values must match field names in order and type 43

44 INSERT Statement 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 id 12 Jonathan Liperi 13 Jeffrey Listfield 14 Sue Smith Fig Authors after an INSERT operation to add a record. 44

45 The Update Statement Modifies data in a table General Form: update table-name set field1=value1 where criteria Example: update authors set firstname='stephen' where lastname='gilbert' and firstname='steve' What happens if you violate an integrity rule? 45

46 UPDATE Statement 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 13 Jeffrey Listfield 14 Sue Jones Fig Table Authors after an UPDATE operation to change a record. 46

47 The Delete Statement Removes data from a table General Form: delete from table-name where criteria Don't forget the criteria!!! Example: delete from authors where lastname='gilbert' 47

48 DELETE Statement 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 13 Jeffrey Listfield Fig Table Authors after a DELETE operation to remove a record. 48

49 Programming g 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 49

50 Displaying ing a Database Table in a DataGridView Step 1: Creating the Project Step 2: Adding a Data Source to the Project Step 3: Choosing the Data Source Type to Add to the Project Step 4: Adding a New Database Connection Step 5: Choosing the Books.mdf Data Connection Step 6: Saving the Connection String 50

51 Step 1: Creating the Project Create a new Windows Application named DisplayTable. Change the Form name to DisplayTableForm and change the source file name to DisplayTable.cs.. Then set the Form's Text property to Display Table. 51

52 Step 2: Adding a Data Source to the Project To interact with a data source (e.g., a database), you must add it to the project using the Data Sources window, which lists the data that your project can access. Open the Data Sources window by selecting Data > Show Data Sources or by clicking the tab to the right of the tab for the Solution Explorer. In the Data Sources window, click Add New Data Source... to open the Data Source Configuration Wizard. This wizard guides you through connecting to a database and choosing the parts of the database you will want to access in your project. 52

53 Step 2: Adding a Data Source to the Project 53

54 Step 3: Choosing the Data Source Type to Add to the Project The first screen of the Data Source Configuration Wizard asks you to choose the data source type you wish to include in the project. Select Database and click Next >. 54

55 Step 4: Adding a New Database Connection You must next choose the connection that will be used to connect to the database (i.e., the actual source of the data). Click New Connection... to open the Add Connection dialog. If the Data Source is not set to Microsoft SQL Server Database File (SqlClient), click Change..., select Microsoft SQL Server Database File and click OK. In the Add Connection dialog, click Browse..., locate the Books.mdf database file on your computer, select it and click Open. You can click Test Connection to verify that t the IDE can connect to the database through SQL Server. Click OK to create the connection. 55

56 Step 4: Adding a New Database Connection 56

57 Step 5: Choosing the Books.mdf Data Connection Now that you have created a connection to the Books.mdf database, you can select and use this connection to access the database. Click Next > to set the connection, then click Yes when asked whether you want to move the database file to your project. 57

58 Step 5: Choosing the Books.mdf Data Connection 58

59 Step 6: Saving the Connection String The next screen asks you whether h you want to save the connection string to the application configuration file. A connection string specifies the path to a database file on disk, as well as some additional settings that determine how to access the database. Saving the connection string in a configuration file makes it easy to change the connection settings at a later time. Leave the default selections and click Next > to proceed. 59

60 Step 6: Saving the Connection String 60

61 Displaying a Database Table in a DataGridView cont d Step 7: Selecting the Database Objects to Include in Your Dataset Step 8: Viewing the Data Source in the Data Sources Window Step 9: Viewing the Database in the Solution Explorer 61

62 Step 7: Selecting the Database Objects to Include in Your DataSet The IDE retrieves information about the database you selected and prompts p you to select the database objects (i.e., the parts of the database) that you want your project to be able to access. Recall that programs typically access a database's contents through a cache of the data, which is stored in a DataSet. In response to your selections in this screen, the IDE will generate a class derived from System.Data.DataSet that is designed specifically to store data from the Books database. Click the checkbox to the left of Tables to indicate that the custom DataSet should cache (i.e., locally store) the data from all the tables in the Books databaseauthors, AuthorISBN and Titles. By default, the IDE names the DataSet BooksDataSet, though it is possible to specify a different name in this screen. Finally, click Finish to complete the process of adding a data source to the project. 62

63 Step 7: Selecting the Database Objects to Include in Your DataSet 63

64 Step 8: Viewing the Data Source in the Data Sources Window Notice that a BooksDataSet node now appears in the Data Sources window with child nodes for each table in the Books databasethese nodes represent the DataTables of the BooksDataSet. Expand the Authors node and you will see the table's columnsthe DataSet's structure mimics that of the actual Books database 64

65 Step 8: Viewing the Data Source in the Data Sources Window 65

66 Step 9: Viewing the Database in the Solution Explorer Books.mdf is now listed as a node in the Solution Explorer, indicating that the database is now part of this project. In addition, the Solution Explorer now lists a new node named BooksDataSet.xsd. A file with the.xsd extension is an XML Schema document, which specifies the structure of a set of XML documents. The IDE uses an XML Schema document to represent a DataSet's structure, including the tables that comprise the DataSet and the relationships among them. When you added the Books database as a data source, the IDE created the BooksDataSet.xsd file based on the structure of the Books database. The IDE then generated class BooksDataSet from the schema (i.e., structure) described by the.xsd file. 66

67 Step 9: Viewing the Database in the Solution Explorer 67

68 Displaying the Authors Table Now that you have added the Books database as a data source, you can display the data from the database's Authors table in your program. The IDE provides design tools that allow you to display data from a data source on a Form without writing any code. Simply drag and drop items from the Data Sources window onto a Form, and the IDE generates the GUI controls and code necessary to display the selected data source's content. To display the Authors table of the Books database, drag the Authors node from the Data Sources window to the Form. The IDE generates two GUI controls that appear on DisplayTableFormauthorsBindingNavigator g and authorsdatagridview. The IDE also generates several additional non-visual components that appear in the component traythe gray region below the Form in Design view. We use the IDE's default names for these autogenerated components (and others throughout the chapter) to show exactly what the IDE creates. We briefly discuss the authorsbindingnavigator and authorsdatagridview controls here. The next section discusses all of the autogenerated components in detail and explains how the IDE uses these components to connect the GUI controls to the Authors table of the Books database. 68

69 Design view after dragging the Authors data source node to the Form 69

70 Displaying the Authors table in a DataGridView A DataGridView displays data organized in rows and columns that correspond to the rows and columns of the underlying data source. In this case, the DataGridView displays the data of the Authors table, so the control has columns named AuthorID, FirstName and LastName. In Design view, the control does not display any rows of actual data below the column headers. The data is retrieved from the database and displayed in the DataGridView only at runtime. Execute the program. When the Form loads, the DataGridView contains four rows of dataone for each row of the Authors table 70

71 Displaying the Authors table in a DataGridView 71

72 Binding Navigator The strip of buttons below the title bar of the window is a BindingNavigator, which enables users to browse and manipulate data displayed by another GUI control (in this case, a DataGridView) on the Form. A BindingNavigator's buttons resemble the controls on a CD or DVD player and allow you to move to the first row of data, the preceding row, the next row and the last row. The control also displays the currently selected row number in a text box. You can use this text box to enter the number of a row that you want to select. The authorsbindingnavigator in this example allows you to "navigate" the Authors table displayed in the authorsdatagridview. Clicking the buttons or entering a value in the text box causes the DataGridView to select the appropriate row. An arrow in the DataGridView's leftmost column indicates the currently selected row. A BindingNavigator also has buttons that allow you to add a new row, delete a row and save changes back to the underlying data source (in this case, the Authors table of the Books database). Clicking the button with the yellow plus icon () adds a new row to the DataGridView. However, simply typing values in the FirstName and LastName columns does not insert a new row in the Authors table. To add the new row to the database on disk, click the Save button (the button with the disk icon, ). Clicking the button with the red X () deletes the currently selected row from the DataGridView. Again, you must click the Save button to make the change in the database. Test these buttons. Execute the program and add a new row, then save the changes and close the program. When you restart the program, you should see that the new row was saved to the database and appears in the DataGridView. Now delete the new row and click the Save button. Close and restart the program to see that the new row no longer exists in the database. 72

73 Querying the Books Database Step 1: Creating the Project Step 2: Adding a Data Source to the Project Step 3: Creating a DataGridView to Display the Titles Table Step 4: Adding Custom Queries to the TitlesTableAdaptor Step 5: Choosing How the TableAdapter Schould Access the Database 73

74 Querying the Books Database cont d Step 6: Choosing the Query Rype Step 7: Specifying a SELECT Statement for the Query Step 8: Building a Query with Query Builder Step 9: Closing the Query Builder Step 10: Setting the Names of the Autogenerated Methods That Perform the Query Step 11: Adding an Additional Query 74

75 Querying the Books Database cont d Step 12: Adding a ComboBox to the Step 13: Customizing i the Form s Load Event Handler Step 14: Programming an Event Handler for the ComboBox 75