1. 242-301 Adv. CoE Lab: JDBC 1 Advanced Computer Engineering Lab Objective – –to give some background on JDBC to help with the lab exercises 242-301, Semester 1, 2014-2015 Introduction to Java Database Connectivity (JDBC)

2. 242-301 Adv. CoE Lab: JDBC 2 Overview 1. What is JDBC? 2. The JDBC-ODBC Bridge 3.Four Types of JDBC Drivers 4.JDBC Pseudocode 5. SimpleJDBC.java Continued

3. 242-301 Adv. CoE Lab: JDBC 3 6. Meta Data 7. Using MS Access 8. Books.accdb as an ODBC Data Source 9.Data Source Problems 10.More Information

4. 242-301 Adv. CoE Lab: JDBC 4 1. What is JDBC? JDBC is an interface which allows Java code to execute SQL statements inside relational databases – –the databases must follow the ANSI SQL-2 standard

5. 242-301 Adv. CoE Lab: JDBC 5 JDBC in Use Java program connectivity data processing utilities JDBC driver for Oracle driver for Sybase jdbc-odbc bridge odbc driver Green means "Java code"

6. 242-301 Adv. CoE Lab: JDBC 6 2. The JDBC-ODBC Bridge ODBC (Open Database Connectivity) is a Microsoft standard from the mid 1990’s. It is an API that allows C/C++ programs to execute SQL inside databases ODBC is supported by many products. Continued

7. 242-301 Adv. CoE Lab: JDBC 7 The JDBC-ODBC bridge allows Java code to use the C/C++ interface of ODBC – –it means that JDBC can access many different database products The layers of translation (Java --> C --> SQL) can slow down execution. Continued

8. 242-301 Adv. CoE Lab: JDBC 8 The JDBC-ODBC bridge comes free with the JDK: – –called sun.jdbc.odbc.JdbcOdbcDriver The ODBC driver for Microsoft Access comes with MS Office – –so it is easy to connect Java and Access

9. 242-301 Adv. CoE Lab: JDBC 9 3. Four Types of JDBC Driver 1. JDBC-ODBC Bridge (type 1) – –translate Java to the ODBC API – –used by many Windows-based databases, e.g. MS-Access 2. Database Protocol Driver (type 4) – –Independent from the OS/hardware because the driver is in Java. Continued

10. 242-301 Adv. CoE Lab: JDBC 10 3. Native API Connection Driver (type 2) – –connected by a OS native module, dependent on the OS or hardware (e.g. DLLs on Windows) 4. Net Connection Driver (type 3) – –use Java to access the database via networking middleware (usually TCP/IP) – –required for networked applications

11. 242-301 Adv. CoE Lab: JDBC 11 JDBC Drivers A very long list of drivers (freeware, shareware, and commercial) can be found at: http://www.oracle.com/technetwork/java/ index-136695.html

12. 242-301 Adv. CoE Lab: JDBC 12 4. JDBC as a Diagram DriveManagerConnectionStatementResultSet creates Driver SQL data make link to driver Green means "Java code"

13. 242-301 Adv. CoE Lab: JDBC 13 DriveManager It is responsible for establishing the connection to the database through the driver. e.g. Class.forName( "sun.jdbc.odbc.JdbcOdbcDriver"); Connection conn = DriveManager.getConnection(url); name of the database

14. 242-301 Adv. CoE Lab: JDBC 14 Name the Database The name and location of the database is given as a URL – –the details of the URL vary depending on the type of database that is being used

15. 242-301 Adv. CoE Lab: JDBC 15 ODBC Database URL jdbc:odbc: //host.domain.com: 2048 /data/file The comms protocol The machine holding the database. The port used for the connection. The path to the database on the machine e.g. jdbc:odbc:Books

16. 242-301 Adv. CoE Lab: JDBC 16 Statement Object The Statement object provides a ‘workspace’ where SQL queries can be created, executed, and results collected. e.g. Statement st = conn.createStatement(): ResultSet rs = st.executeQuery( “ select * from Authors” ); : st.close();

17. 242-301 Adv. CoE Lab: JDBC 17 ResultSet Object Stores the results of a SQL query. A ResultSet object is similar to a ‘table’ of answers, which can be examined by moving a ‘pointer’ (cursor). Continued

18. 242-301 Adv. CoE Lab: JDBC 18 Cursor operations: – –first(), last(), next(), previous(), etc. Typical code: while( rs.next() ) { // process the row; } 23 5 17 98 John Mark Paul Peter cursor

19. 242-301 Adv. CoE Lab: JDBC 19 5. SimpleJDBC.java // SimpleJDBC.java // Displays the firstnames and lastnames // of the Authors table in the Books db. import java.sql.*; public class SimpleJDBC { public static void main(String[] args) { // The URL for the Books database. // ’Protected' by a login and password. String url = "jdbc:odbc:Books"; String username = "anonymous"; String password = "guest"; :

20. 242-301 Adv. CoE Lab: JDBC 20 try { // load the JDBC-ODBC Bridge driver Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); // connect to db using DriverManager Connection conn = DriverManager.getConnection( url, username, password ); // Create a statement object Statement statement = conn.createStatement(); // Execute the SQL query ResultSet rs = statement.executeQuery( "SELECT lastName, firstName FROM Authors" ); :

21. 242-301 Adv. CoE Lab: JDBC 21 // Print the result set while( rs.next() ) System.out.println( rs.getString("lastName") + ", " + rs.getString("firstName") ); // Close down statement.close(); conn.close(); } :

22. 242-301 Adv. CoE Lab: JDBC 22 catch ( ClassNotFoundException cnfex ) { System.err.println( "Failed to load JDBC/ODBC driver." ); cnfex.printStackTrace(); System.exit( 1 ); // terminate program } catch ( SQLException sqlex ) { System.err.println( sqlex ); sqlex.printStackTrace(); } } // end of main() } // end of SimpleJDBC class

23. 242-301 Adv. CoE Lab: JDBC 23 Section 8 not done. Section 8 now done. Output

24. 242-301 Adv. CoE Lab: JDBC 24 If you've done section 8, but still getting error messages, then check out section 9. If you've done section 8, but still getting error messages, then check out section 9. If you're still having problems, please come to see Aj. Andrew. If you're still having problems, please come to see Aj. Andrew.

25. 242-301 Adv. CoE Lab: JDBC 25 5.1. Username & Password The database’s link to the outside (e.g. its ODBC interface) must be configured to have a login and password – –details for ODBC are given later

26. 242-301 Adv. CoE Lab: JDBC 26 5.2. Accessing a ResultSet The ResultSet class contains many methods for accessing the value of a column of the current row – –can use the column name or position – –e.g. get the value in the lastName column: rs.getString("lastName") Continued

27. 242-301 Adv. CoE Lab: JDBC 27 The ‘tricky’ aspect is that the values are SQL data, and so must be converted to Java types/objects. There are many methods for accessing/converting the data, e.g. – –getString(), getDate(), getInt(), getFloat(), getObject()

28. 242-301 Adv. CoE Lab: JDBC 28 6. Meta Data Meta data is the information about the database: – –e.g. the number of columns, the types of the columns – –meta data is the schema information IDNameCourseMark 007James BondShooting99 008Aj. AndrewKung Fu1 meta data

29. 242-301 Adv. CoE Lab: JDBC 29 One important use for metadata is for formatting result set data One important use for metadata is for formatting result set data –e.g. instead of displaying the results as text, display them in a Java table with headers, rows, columns see TableDisplay.java in the Exercises see TableDisplay.java in the Exercises

30. 242-301 Adv. CoE Lab: JDBC 30 6.1. Accessing Meta Data The getMetaData() method can be used on a ResultSet object to create its meta data object. e.g. ResultSetMetaData md = rs.getMetaData();

31. 242-301 Adv. CoE Lab: JDBC 31 6.2. Using Meta Data int numCols = md.getColumnCount(); for (int i = 0; i <= numCols; i++) { if (md.getColumnType(i) == Types.CHAR) System.out.println( md.getColumnName(i) ) }

32. 242-301 Adv. CoE Lab: JDBC 32 6.3. More Meta Data Methods getTableName() getPrecision() – –number of decimal digits in the column isSigned() – –returns true if column has signed numbers isCurrency() etc.

33. 242-301 Adv. CoE Lab: JDBC 33 7. Using MS Access MS Access changed its file formats when Access 2007 was released: MS Access changed its file formats when Access 2007 was released: –for Access 2003 (and earlier) you should use Books.mdb –for Access 2007 or 2010, you should use Books.accdb –both versions are in the lab's website.

34. 242-301 Adv. CoE Lab: JDBC 34 Access and SQL How to use SQL in Access is described at: How to use SQL in Access is described at: –http://www.jaffainc.com/SQLStatementsInAccess.htm And on the website, in sqlAccess2007.txt and sql_intr.pdf

35. 242-301 Adv. CoE Lab: JDBC 35 TableRelationships in Books.accdb (and Books.mdb) Under Database Tools > Relationships

36. 242-301 Adv. CoE Lab: JDBC 36 8. Books.accdb as an ODBC Data Source 1. Click on “Data Sources (ODBC)” in “Administrative Tools” folder in the Control Panel.

37. 242-301 Adv. CoE Lab: JDBC 37 Select the MS Access Data Source. Select the MS Access Data Source. Press “Add’ to add a data source. If you don't find MS Access here, then go to Section 9.

38. 242-301 Adv. CoE Lab: JDBC 38 Select the English Microsoft Access Driver (*.mdb, *.accdb). Press “Finish”.

39. 242-301 Adv. CoE Lab: JDBC 39 3. Type in the "Books" source name, any description, and press “Select” to browse to set the path to the Books.accdb or Books.mdb file. Click on “Advanced”.

40. 242-301 Adv. CoE Lab: JDBC 40 4. Type in a username and password ( guest ). Click “Ok” repeatedly until all the dialog boxes are gone.

41. 242-301 Adv. CoE Lab: JDBC 41 9. Data Source Problems Two problems may occur when using JDBC with the data source set up in Section 8: Two problems may occur when using JDBC with the data source set up in Section 8: –"No suitable driver found for jdbc: odbc: driver={Microsoft Access Driver (*.mdb)};... –"The specified DSN contains an architecture mismatch between the Driver and Application" These problems are usually due to you using the 64-bit version of Windows 7. These problems are usually due to you using the 64-bit version of Windows 7.

42. 242-301 Adv. CoE Lab: JDBC 42 Check your version of Windows by following the steps listed at: Check your version of Windows by following the steps listed at: –http://support.microsoft.com/kb/827218 means 32-bit

43. 242-301 Adv. CoE Lab: JDBC 43 Which Version of Access? Check whether you are using the 32-bit or 64-bit version of Access: Check whether you are using the 32-bit or 64-bit version of Access: –look at the "Help" dialog

44. 242-301 Adv. CoE Lab: JDBC 44 Win7 64-bit & Access 64-bit You may need to download the 64-bit Access drivers from: You may need to download the 64-bit Access drivers from: –http://www.microsoft.com/ en-us/download/details.aspx?id=13255 –execute –execute AccessDatabaseEngine_x64.exe You should also be using the 64-bit version of Java for Windows. get it from: You should also be using the 64-bit version of Java for Windows. get it from: –http://www.java.com/en/download/

45. 242-301 Adv. CoE Lab: JDBC 45 Win 7 64-bit & Access 32-bit Set up the data source using the 32-bit ODBC control panel at: Set up the data source using the 32-bit ODBC control panel at: –c:\windows\sysWOW64\odbcad32.exe You should also be using the 32-bit version of Java for Windows. Get it from: You should also be using the 32-bit version of Java for Windows. Get it from: –http://www.java.com/en/download/

46. 242-301 Adv. CoE Lab: JDBC 46 10. More Information Ivor Horton’s Beginning Java 2, JDK 5 Edition, Wiley Publishing, 2005 Chapters 24 and 25 (starts on p.1306) Advanced Java 2 Platform: How to Program Deitel & Deitel, Prentice-Hall, 2001 Chapter 8 http://java.coe.psu.ac.th/ForMember/ Continued

47. 242-301 Adv. CoE Lab: JDBC 47 JDBC Wikipaedia page: http://en.wikipedia.org/wiki/JDBC_driver The Java Documentation and tutorial – –http://docs.oracle.com/javase/tutorial/ – –the JDBC Database Access ‘trail’ is very good – –http://docs.oracle.com/javase/tutorial/ jdbc/index.html