1. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 1 Lecture 8 Object Oriented Programming in Java Advanced Topics Java Database Connectivity (JDBC)

2. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 2 Today’s Lecture Trail: JDBC(TM) Database Access Lesson: JDBC Basics Other resource: JDBC Short Course –http://developer.java.sun.com/developer/onlineTraining/Database/JDBCShortCourse/index.html

3. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 3 History Structured Query Language (SQL) ODBC JDBC

4. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 4 Data Definition Language creating databases creating tables and columns creating indexes examples –CREATE TABLE tablename …. –CREATE INDEX anindexname ….

5. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 5 Data Manipulation Language inserting records deleting records updating records examples: –SELECT * FROM atable WHERE fieldname = ‘avalue’ –INSERT INTO atable VALUES(‘field1’,’field2’,’field3’) –DELETE FROM atable WHERE fieldname = ‘avalue’

6. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 6 Common Programming Steps With JDBC: –load drivers –connect to a database –create SQL statement –send SQL to database –disconnect from database

7. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 7 Step 1: Loading Drivers Sun’s provided driver –JDBC-ODBC bridge driver –good for prototyping –not to be used for real production applications Register the driver: –DriverManager.registerDriver(new sun.jdbc.odbc.JdbcOdbcDriver())

8. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 8 Design Point –Guess what is the type of the parameter to the DriverManager’s registerDriver method? –What is the design significance?

9. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 9 Step 2: Connecting DriverManager’s getConnection method –several ways to specify the required parameters DriverManager.getConnection(URL,userid,password) Connection getConnection(URL,properties) Connection getConnection(URL) getConnection returns an object of type “Connection”

10. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 10 Design Point –multiple ways to connect –Use of public static methods to create a Connection object: factory design pattern –private constructor to prevent from instantiating the class –Connection is an interface

11. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 11 Steps 3 & 4: Create and Send a SQL Statement use the connection to create the statement –Statement sql = con.createStatement(); create a String with the SQL statement –String s = “INSERT INTO tablename VALUES(\’field1\’, \’field2\’)”; send the statement to the driver/database –sql.execute(s);

12. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 12 Step 5: Disconnect close the connection once you are done with it example: –Connection con; –…. –con.close();

13. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 13 Getting data from a database SQL –SELECT field1, field2, field3 FROM atablename use Statement executeQuery method –ResultSet resultSet = sql.executeQuery(“…”)

14. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 14 Handling Result Sets the ResultSet class allows you to iterate through the rows returned by the SQL statement String s while(resultSet.next()){ –s = resultSet.getString(“field1”); }

15. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 15 Getting Metadata ResultSetMetadata meta = resultSet.getMetaData(); int numOfColumns = meta.getColumnCount(); String s = meta.getColumnLabel(1); String s = meta.getColumnTypeName();

16. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 16 Multiple execute methods for INSERT, UPDATE, DELETE: –stmt.executeUpdate(“...”); for obtaining result sets –ResultSet rs = stmt.executeQuery(“...”);

17. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 17 Prepared Statement used for efficiency when the same statement will be used multiple times PreparedStatement prepared = connection.prepareStatement(“INSERT …”);

18. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 18 synchronizing updates connection.commit();

19. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 19 JDBC Hands-on - I Problem statement; –first, we will create a small database using either the text file or Access ODBC drivers. The database-table will have the following fields; –FirstNameVARCHAR –LastNameVARCHAR –GradeINTEGER –second, we will create a Java program that inserts and reads records into/from the database-table –third, we will look at the metadata of the database- table

20. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 20 JDBC Hands-on - II configure a Data Source Name –Bring up Control Panel »Select the Start button »Select the Settings menu item »Select the Control Panel menu item –Find and double-click on the ODBC Icon (32-bit/with 32 on it). This brings up the 'Data Sources' window. »Select Add. This brings up the Add Data Source window. –Select the driver for the type of driver you want. »If you selected Text, the ODBC Text Setup window appears. »Name the data source mage. »Fill in a description. »Select the directory in which you placed files from the initial task. –Select OK to accept new driver.

21. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 21 JDBC Hands-on - III Create an empty text file which will later contain your data make sure the text file is in the directory specified when configuring the DSN

22. June 1, 2000 Object Oriented Programming in Java (95-707) Java Language Basics 22 JDBC Hands-on - IV Edit a Java program to start using the defined DSN Sample program import java.sql.*; public class JDBCTest{ public static void main(String arg[]) throws Exception{ DriverManager.registerDriver(new sun.jdbc.odbc.JdbcOdbcDriver()); Connection con = DriverManager.getConnection("jdbc:odbc:dsnname"); Statement s = con.createStatement(); s.execute("INSERT INTO file.txt VALUES(“..."); s.execute("INSERT INTO file.txt VALUES(“...”); …. con.close(); }