1. HW#4 Making Simple BBS Using JDBC
Jaesoo Yoo
Chungbuk National University

2. Contents Introduction to JDBC HW Assignment Directions for HW
Example
Main classes & methods
JDBC driver installationnt program installation
HW Assignment
Directions for HW
References

3. JDBC Introduction to JDBC Example Main classes & method
JDBC driver installation

4. Introduction to JDBC What is JDBC? “Java Database Connectivity”
Connector to access DB, when developing applications in JavaTM Platform
JDBC
API
Driver
DBMS
Application
SQL statement
ResultSet

5. <An example code: Test.java>
import java.sql.*;
class Test {
public static void main(String[] args) {
Connection con = null;
Statement stmt = null;
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection( "user", "passwd");
stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select name from product");
while (rs.next()) {
String product = rs.getString(1);
System.out.println(product); }
} catch (Exception e) {
e.printStackTrace();
} finally {
if (stmt != null) stmt.close();
if (con != null) con.close();
} catch (Exception e) { }
<An example code: Test.java>

6. Class.forName(“oracle.jdbc.driver.OracleDriver”);
Main classes & method
Loading JDBC driver
Using Class.forName()
Connecting to DB
Using DriverManager.getConnection()
is URL
Class.forName(“oracle.jdbc.driver.OracleDriver”);
Connection con =
DriverManager.getConnection("jdbc:oracle:thin:
@dbserver.chungbuk.ac.kr", "user", "passwd");

7. Main classes & method (cont’d)
Executing queries
Using Statement class
Using PreparedStatement class
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select name from product");
PreparedStatement pstmt =
con.prepareStatement(“insert into product values(?, ?)”);
pstmt.setString(1, “mp3”);
pstmt.setInt(2, 150);
pstmt.executeUpdate();
※ Use executeUpdate() for insert, update, and delete

8. Main classes & method (cont’d)
Cursor operations
Use methods of ResultSet class
Ex) next(), getString(), etc.
ResultSet rs = stmt.executeQuery("select name from product");
while (rs.next()) {
String product = rs.getString(1);
System.out.println(product); }

9. Main classes & method (cont’d)
Using ‘finally’
Before finishing code, connection should be closed
try { …
con = DriverManager.getConnection( … );
stmt = con.createStatement();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (stmt != null) stmt.close();
if (con != null) con.close();
} catch (Exception e) {} }

10. Main classes & method (cont’d)
Executing Query within a Transaction
try { …
con = DriverManager.getConnection( … );
con.setAutoCommit(false);
stmt = con.createStatement();
stmt.executeQuery( … );
conn.commit();
} catch (SQLException e) {
conn.rollback(); }

11. JDBC driver installation
JAVA SDK1.6 or 1.7 must be installed
Download (ojdbc6.jar)
Environment variable setting
Add to the CLASSPATH environment variable the driver installation path
Ex) If the path is c:\Oracle\jdbc\ojdbc6.jar

12. JDBC driver installation (cont’d)
Example file execution
Compiling & running in a DOS command window
import java.sql.*;
class Test {
public static void main(String[] args) {
Connection con = null;
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection( "user", "passwd");
System.out.println(“Connection created");
} catch (Exception e) {
e.printStackTrace();
} finally {
if (con != null) con.close();
} catch (Exception e) { } }

13. Eclipse Setting Working on Eclipse IDE
Add ojdbc6.jar to project build path
Right click on JRE System Library  Build Path  Configure Build Path

14. Eclipse Setting (cont’d)
Working on Eclipse IDE
Add External IDE  select ojdbc6.jar

15. Overview Homework Assignment Directions References

16. Overview Simple BBS manages user accounts
supports write/read/delete/show commands
transaction control
uses two tables ARTICLES and USERS in DB
ARTICLES: contains users’ articles
USERS: stores user account info.
ARTICLES
USERS
NO: INT
WRITER: VARCHAR2(10)
COUNT: INT
TITLE: VARCHAR2(30)
CONTENT: VARCHAR2(500)
USERID VARCHAR2(10)
PASSWD VARCHAR2(10)

17. Homework #4 Initial screen user can login to BBS, or
create a new account by typing ‘new’

18. Homework #4 (cont’d) HW4-1) Managing user accounts
Create a new account
check if there exists the same ID

19. Homework #4 (cont’d) HW4-1) Managing user accounts (cont’d)
Login to BBS
If a user type a wrong ID or password three times, login is denied and the program exits.

20. Homework #4 (cont’d) HW4-2) Command: show(s)/quit(q) type ‘s’;
show the catalog of user articles in the order of article number (no)
type ‘q’;
BBS program exits

21. Homework #4 (cont’d) HW4-3) Command: read(r) & transaction control
type ‘r’; select article number(no);
show the title and content of the selected article
increase count by one after a user read this article

22. Homework #4 (cont’d) HW4-4) Command: write(w)
type ‘w’; enter title; input content;
Note that entering content ends with the carriage return

23. Homework #4 (cont’d) HW4-5) Command: delete(d)
type ‘d’; select article number(no);
Note that a user cannot delete the others’ articles

24. Homework #4 (cont’d) HW4-5) Command: delete(d) (cont’d)
After deletion, rearrange the article numbers

25. Submission Files to submit How to submit Due date
1. JAVA (*.java) files that implement the Simple BBS
How to submit
조교)
Due date
December 21 (Sunday), 11:59 pm.

26. References JDBC documentation
JAVA Platform, Standard Edition 6 API Specification
documentation