JDBC
Java Database Connectivity
1
Agenda
Relational Database Model
 Structured Query Language
 JDBC

 API
Overview
 JDBC Architecture
 JDBC Features

Using JDBC API
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Relational Database Model

Database models
 Hierarchal,
network, relational (most popular)
 Focus on relational

Relational Database Model
 Logical
representation of data
 Consider relationships between data

Not concerned with implementation
3
Relational Database Model

Relational database
 Composed
of tables
Rows called records
 Columns are fields (attributes)

 First
field usually primary key
Unique for each record
 Primary key can be more than one field (column)
 Primary key not required

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Relational Database Model
Relational Database Structure
Table: Employee
A record
Number
Name
Department Salary
Location
23603
JONES, A.
413
1100
NEW JERSEY
24568
KERWIN, R.
413
2000
NEW JERSEY
34589
LARSON, P.
642
1800
LOS ANGELES
35761
MYERS, B.
611
1400
ORLANDO
47132
NEUMANN, C.
413
9000
NEW JERSEY
78321
STEPHENS, T.
611
8000
ORLANDO
Primary Key
A column
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Relational Database Overview

Books.mdb database Structure:
 Primary
key in bold
 Rule of Entity Integrity

Every record has unique entry in primary key
field
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Structured Query Language

Overview of SQL
 Context of Books.mdb database
 SQL keywords discussed in context
of complete
queries

Some keywords beyond scope of text
 Used to
 Query a database
 Insert records into a database
 Update existing records in a database

SQL keywords
 SELECT,
FROM, WHERE, GROUP BY, HAVING,
ORDER BY
 INSERT, UPDATE, DELETE, etc
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Structured
Query
Language
 Example SQL Query:

SELECT * FROM Titles
WHERE Title LIKE '*How to Program'
ORDER BY Title ASC
SQL Result:
ISBN
Title
0-13-118043-6
0-13-226119-7
0-13-528910-6
0-13-016143-8
C How to Program
C How to Program
C++ How to Program
Internet and World Wide Web How
to Program
Java How to Program
Java How to Program
Visual Basic 6 How to Program
0-13-012507-5
0-13-899394-7
0-13-456955-5
Edition Year
Publisher
Number Published ID
1
2
2
1
1992
1994
1997
1999
1
1
1
1
3
2
1
1999
1997
1998
1
1
1
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JDBC – API Overview

JDBC API makes it possible to do three
things:
 Establish
a connection with a database or
access any tabular data source
 Send SQL statements
 Process the results
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JDBC Architecture for Java
Application
Type 1
Type 2
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JDBC Architecture for Java Applet
Type 4
Type 3
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JDBC Features







Leverage Existing Enterprise
Data
Simplified Enterprise
Development : Easy to use API
Zero Configuration for Network
Computers
Full Access to Metadata
No Installation
Database Connection
Identified by URL
Supported by many industry
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JDBC Features

From java.sql.*: (standard)
 Scrollable result set: MoveNext, MovePrev
 Updatable result set
 Supported BLOB and CLOB
 Batch updates: performance improvement,
sending
multiple updated instead of single updated to DB
 Savepoints: Ability to roll transactions back to where a
savepoint is set

From javax.sql.* (optional):
 Connection pooling
 Distributed transactions
 JNDI support
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Using JDBC API

Setup Database and JDBC Driver
 Ex:

Books.mdb using JdbcOcbd bridge
Loading Driver
 Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”);

Making Connection
 Connection
con =
DriverManager.getConnection(“jdbc:odbc:books”,
“userName”, “password”);

Send/Execute Query
 Statement stmt = con.createStatement();
 ResultSet rs = stmt.executeQuery(“SELECT
Authors”);
* from
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Setup Books.mdb Database
Setup dialog appears. Enter name used to reference database
and
description
(optional).
ODBC
Data Source
Administrator
now has Books. We
candata
nowsource
accessmust be registered with
The
Use Select... to choose
database
file.
This allows
to register
ourGo to
ODBC
data us
source
using
system.
JDBC
to Control Panel -> ODBC
Use
Advanced...
toData
create
a username
(anonymous) and
User
Data
Source
Name.
ODBC
driver.
Source
Administrator.
password (guest). When done, click OK
Go to the User DSN tab and
click Add...
We are using Access, so select
Microsoft Access Driver,
then Finish
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Statement for SELECT Query

For Forward Only and Read Only
ResultSet
 Statement

stmf = con.createStatement();
For Updateable ResultSet (JDBC 2.0)
 Statement
stmt = con.createStatement(
ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
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ResultSet Record Navigation

Record Navigation
 next();
 MovePrev  previous();
 Last Record  afterLast(); isAfterLast()
 First Record  beforeFirst(); isBeforeFirst()
 Go to N position  absolute(n), relative(n)
 Record Count  int recCount = rs.getRow();
 MoveNext
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First Sample

Perform query on Books.mdb database
 Connect
to database
 Query to Table “Authors”
 Display results
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First Sample

Authors table
 Four
fields
AuthorID - ID number
 FirstName
 LastName
 YearBorn

AuthorID
1
FirstName
Harvey
LastName
Deitel
YearBorn
1946
2
Paul
Deitel
1968
3
Tem
Nieto
1969
19
1 // Fig. 18.24: TableDisplay.java
2 // This program displays the contents of the Authors table
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// in the Books database.
import java.sql.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
Import the sql package.
10 public class TableDisplay extends JFrame {
Specify url, username, and
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private Connection connection;
password. The database has
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private JTable table;
password protection (next
13
section).
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public TableDisplay()
15
{
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// The URL specifying the Books database to which
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// this program connects using JDBC to connect to a
// Microsoft ODBC database.
String url = "jdbc:odbc:Books";
Load class definition for database driver
String username = "anonymous";
(static method Class.forName).
String password = "guest";
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// Load the driver to allow connection to the database
Attempt to connect to
try {
Use static method
Class.forName( "sun.jdbc.odbc.JdbcOdbcDriver" );
connection = DriverManager.getConnection(
url, username, password );
database.
getConnection, of class
DriverManager (java.sql).
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}
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catch ( ClassNotFoundException cnfex ) {
System.err.println(
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"Failed to load JDBC/ODBC driver." );
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cnfex.printStackTrace();
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System.exit( 1 );
}
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catch ( SQLException sqlex ) {
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System.err.println( "Unable to connect" );
sqlex.printStackTrace();
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}
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getTable();
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setSize( 450, 150 );
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show();
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}
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private void getTable()
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{
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Statement statement;
ResultSet resultSet;
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// terminate program
Create a Statement object that
will query the database.
try {
String query = "SELECT * FROM Authors";
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statement = connection.createStatement();
resultSet = statement.executeQuery( query );
Returns a ResultSet object
containing results.
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displayResultSet( resultSet );
statement.close();
}
catch ( SQLException sqlex ) {
sqlex.printStackTrace();
}
statement closed when
not needed.
}
private void displayResultSet( ResultSet rs )
throws SQLException
{
Positions to first record in ResultSet
// position to first record
(initially before first record).
boolean moreRecords = rs.next();
// If there are no records, display a message
if ( ! moreRecords ) {
JOptionPane.showMessageDialog( this,
"ResultSet contained no records" );
setTitle( "No records to display" );
return;
}
Create new Vectors, similar to
dynamic arrays.
setTitle( "Authors table from Books" );
Vector columnHeads = new Vector();
Vector rows = new Vector();
try {
// get column heads
ResultSetMetaData rsmd = rs.getMetaData();
Get meta data, which
describes contents of
ResultSet.
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for ( int i = 1; i <= rsmd.getColumnCount(); ++i )
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columnHeads.addElement( rsmd.getColumnName( i ) );
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// get row data
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do {
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Get names of column heads,
add to Vector.
rows.addElement( getNextRow( rs, rsmd ) );
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} while ( rs.next() );
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// display table with ResultSet contents
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table = new JTable( rows, columnHeads );
98
JScrollPane scroller = new JScrollPane( table );
99
getContentPane().add(
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scroller, BorderLayout.CENTER );
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validate();
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}
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catch ( SQLException sqlex ) {
104
sqlex.printStackTrace();
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Utility method getNextRow
returns a Vector with row
data. Creates a Vector of
Vectors (like double scripted
array).
Create a JTable, takes
Vector of Vectors and
Vector of column heads.
}
}
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private Vector getNextRow( ResultSet rs,
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ResultSetMetaData rsmd )
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throws SQLException
{
Create Vector to hold one row of data.
Vector currentRow = new Vector();
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for ( int i = 1; i <= rsmd.getColumnCount(); ++i )
switch( rsmd.getColumnType( i ) ) {
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case Types.VARCHAR:
currentRow.addElement( rs.getString( i ) );
break;
case Types.INTEGER:
currentRow.addElement(
Test for column type, add appropriate
new Long( rs.getLong( i ) ) );
type of element to Vector.
break;
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default:
System.out.println( "Type was: " +
rsmd.getColumnTypeName( i ) );
}
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public void shutDown()
{
try {
connection.close();
}
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}
return currentRow;
catch ( SQLException sqlex ) {
System.err.println( "Unable to disconnect" );
sqlex.printStackTrace();
}
}
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public static void main( String args[] )
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{
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final TableDisplay app = new TableDisplay();
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app.addWindowListener(
147
new WindowAdapter() {
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public void windowClosing( WindowEvent e )
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{
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app.shutDown();
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System.exit( 0 );
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}
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}
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);
}
156 }
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Update Query

For INSERT, DELETE, UPDATE use:
 stmt.executeUpdate(“DELETE
YearBorn=1946”);

from Authors where
Bacth Update (JDBC 2.0):
Statement stmt = con.createStatement();
con.setAutoCommit(false);
stmt.addBatch("INSERT INTO employees VALUES
(1000, 'Joe Jones')");
stmt.addBatch("INSERT INTO departments VALUES
(260, 'Shoe')");
int [] updateCounts = stmt.executeBatch();
26
Using Transaction

Transaction processing
 Changes
can be undone
 Interface Connection

Method setAutoCommit
 true
- each SQL statements performed individually
 false - several statements grouped as a transaction

Terminating Statement that executes SQL statements


Method commit - commit changes to database
Method rollback - return database to previous state
 Method getAutoCommit
 Returns auto commit state
27
Using Transaction
con.setAutoCommit(false);
PreparedStatement updateSales = con.prepareStatement(
"UPDATE COFFEES SET SALES = ? WHERE COF_NAME LIKE
?");
updateSales.setInt(1, 50);
updateSales.setString(2, "Colombian");
updateSales.executeUpdate();
PreparedStatement updateTotal = con.prepareStatement(
"UPDATE COFFEES SET TOTAL = TOTAL + ? WHERE
COF_NAME LIKE ?");
updateTotal.setInt(1, 50);
updateTotal.setString(2, "Colombian");
updateTotal.executeUpdate();
con.commit();
con.setAutoCommit(true);
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Reference

http://java.sun.com/jdbc
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