1. Capítulo 23: Conectividad a Bases de Datos con JDBCTM
Resumen Introducción Modelo Relaciona de Bases de Datos Generalidades de las Bases de Datos Relacionales: La Base de datos libros SQL Consulta Básica SELECT La Cláusula WHERE La Cláusula ORDER BY Cómo fusionar varias tablas: INNER JOIN La instrucción INSERT La Instrucción UPDATE La Instrucción DELETE Creación de la base de datos libros en MySQL Manipulación de Bases de Datos con JDBC Conectando y consultanto una base de datos Consultas a la base de datos libros

2. 23.1 Introducción Base de datos DBMS SQL Colección organizada de datos
Las mas popurales son las bases de datos relacionales
DBMS
Sistema Manejador de Bases de Datos (Database management system )
Almacena y organiza los datos
SQL
Bases de datos relacionales
Lenguaje de consulta estructurado (Structured Query Language)

3. 23.1 Introducción (Cont.) RDBMS JDBC
Sistema Manejador de Base de Datos Relacionales
SQL Server, Oracle, Sybase, DB”, Infromix, MySQL
JDBC
Conectividad a Bases de Datos de Java
JDBC driver (controlador) , implementa una interfaz en los programas java para conectarse a diversas bases de datos.

4. 23.2 Modelo de Bases de Datos Relacionales
Base de datos Relacional
Tabla
Filas, columnas
Llave Primaria
Identificador único de los datos
Comandos SQL
Consultas (Queries)

5. 23.2 Modelo de Bases de Datos Relacionales (Cont.)
Numero
Nombre
Departamento
Salario
Ubicacion
23603
Jones
413
1100
New Jersey
24568
Kerwin
413
2000
New Jersey
Fila
34589
Larson
642
1800
Los Angeles
35761
Myers
611
1400
Orlando
47132
Neumann
413
9000
New Jersey
78321
Stephens
611
8500
Orlando
Llave Primaria
Columna
Fig Datos de ejemplo para la tabla Empleado

6. 23.2 Modelo de Bases de Datos Relacionales (Cont.)
Departamento
Ubicacion
413
New Jersey
611
Orlando
642
Los Angeles
Fig Resultado de seleccionar datos distintos de Departamento y Ubicacion
de la tabla Empleado

7. 23.3 Generalidades de las bases de datos relacionales: La Base de datos libros
Cuatro tablas
autores, editoriales, isbnAutor y titulos
Relaciones de las tablas

8. 23.3 Generalidades de las bases de datos relacionales: La Base de datos libros (Cont.)

9. 23.3 Generalidades de las bases de datos relacionales: La Base de datos libros (Cont.)
idEditorial
nombreEditorial 1
Prentice Hall 2
Prentice Hall PTG
Fig. 23.6
Datos de la tabla editoriales

10. 23.3 Generalidades de las bases de datos relacionales: La Base de datos libros (Cont.)

11. 23.3 Generalidades de las bases de datos relacionales: La Base de datos libros (Cont.)

12. 23.3 Generalidades de las bases de datos relacionales: La Base de datos libros (Cont.)
idAutor
isbn 1 2 3 4
Fig
Datos de ejemplo de la tabla isbnAutor .

13. 23.3 Relational Database Overview: The books Database (Cont.)
autores
idAutor
nombrePila
apellidoPaterno
isbnAutor
idAutor
isbn
titulos
isbn
titulo
numeroEdicion
copyright
idEditorial
archivoimagen
precio 1 8 1 8 8
editoriales
idEditorial
nombreEditorial 1
Fig Relaciones de tablas en la base de datos libros

14. SQL descripción general SQL palabras clave (keywords)
SQL keyword
Descripción
SELECT
Recupera datos de una o mas tablas
FROM
Tablas involucradas en cada consulta, se requiere para cada .
WHERE
Criterios de selección que determinan cuales filas se van a
Recuperar, borrar o actualizar
GROUP BY
Criterios para agrupar filas
ORDER BY
Criterios para ordenar filas
INNER JOIN
Fusionar filas de varias tablas
INSERT
Insertar filas en una tabla especificada
UPDATE
Actualizar filas en una tabla especificada
DELETE
Eliminar filas en una tabla especificada
Fig
SQL palabras clave para consultas

15. 23.4.1 Consulta Básica SELECT
SELECT * FROM nombreTabla
SELECT * FROM autores
Recuperar ciertas columnas de la tabla

16. Especificar criterio de selcción
Cláusula WHERE
Especificar criterio de selcción
SELECT columna1, columna2, … FROM NombreTabla WHERE criterio
SELECT titulo, numeroEdicion, copyright
FROM titulos
WHERE copyright > 2000
Operadores de condición en la cláusula WHERE
<, >, <=, >=, =, <>
LIKE
Caracteres comodines % y _

17. Cláusula WHERE (Cont.)

18. Cláusula WHERE(Cont.)

19. WHERE Clause (Cont.)

20. Cláusula ORDER BY opcional
Clausula ORDER BY
Cláusula ORDER BY opcional
SELECT columna1, columna2, … FROM nombreTabla ORDER BY columna ASC
SELECT columna1, columna2, … FROM nombreTabla ORDER BY columna DESC
ORDER BY campos múltiples
ORDER BY columna1 tipoOrden, columna2 tipoOrden, …
Combinar WHERE y ORDER BY

21. 23.4.3 Cláusula ORDER BY (Cont.)

22. 23.4.3 Cláusula ORDER BY (Cont.)

23. 23.4.3 Cláusula ORDER BY (Cont.)

24. 23.4.3 Cláusula ORDER BY (Cont.)

25. 23.4.4 Fusionar datos de varias tablas
Los datos se guardan en tablas separadas para evitar redundacia.
Debido a esto a veces es necesario fusionar datos de varias tablas en una sola consulta

26. 23.4.4 Fusionar datos de varias tablas(Cont.)

27. Inserta una fila dentro de una tabla
La instrucción INSERT
Inserta una fila dentro de una tabla
INSERT INTO nombreTabla ( columna1, … , columnaN )
VALUES ( valor1, … , valorN )
INSERT INTO autores ( nombrePila, apellidoPaterno)
VALUES ( ‘Sue’, ‘Smith’ )
idAutor
nombrePila
apellidoPaterno 1
Harvey
Deitel 2
Paul 3
Tem
Nieto 4
Sean
Santry 5
Sue
Smith
Fig
Datos en la tabla autores, después del INSERT

28. Modicar datos de una tabla
La instrucción UPDATE
Modicar datos de una tabla
UPDATE nombreTabla
SET columna1 = valor1, … , columnaN = valorN
WHERE criterios
UPDATE autores
SET apellidoPaterno = ‘Jones’
WHERE apellidoPaterno = ‘Smith’ AND nombrePila = ‘Sue’
authorID
firstName
lastName 1
Harvey
Deitel 2
Paul 3
Tem
Nieto 4
Sean
Santry 5
Sue
Jones
Fig
Datos en tabla autores después de UPDATE

29. Elimina datos de una tabla
La instrucción DELETE
Elimina datos de una tabla
DELETE FROM nombreTabla WHERE criterios
DELETE FROM autores
WHERE apellidoPaterno = ‘Jones’ AND nombrePila = ‘Sue’
authorID
firstName
lastName 1
Harvey
Deitel 2
Paul 3
Tem
Nieto 4
Sean
Santry
Fig
Datos tabla autores después de DELETE

30. 23.5 Creando Base de Datos libros en MySQL
Fig Executing Cloudscape from a command prompt in Windows 2000.

31. 23.6 Manipulando Bases de Datos con JDBC
Conectarse a una Base de Datos
Consultar una Base de Datos
Desplegar los resultados de la consulta

32. 23.6.1 Conectándose y consultando una base de datos
MostrarAutores
Muestra el contenido completo de la base de datos autores
Despliega el contenido de la tabla en un objeto JTextArea
Ver Ejercicio MostrarAutores

33. 23.6.1 Conectándose y consultando una base de datos (Cont.)
Type
Description 1
The
JDBC - to
ODBC bridge driver
connects Java programs to Microsoft ODBC
(Open Database Connectivity) data sources. The Java 2 Software Development
Kit from Sun Microsystems, Inc. includes the JDBC (
sun.jdbc.odbc.Jd bc
OdbcDriver
). This driver typically requires the
ODBC driver to be installed on the client computer and normally requires
configuration of the ODBC data source. The bridge driver was introduced
primarily for development purposes and should not be used fo
r production
applications. 2
Native
API, partly Java drivers
enable JDBC programs to use database
specific
APIs (normally written in C or C++) that allow client programs to access
databases via the Java Native Interface. This driver type translates JDBC i
nto
database
specific code. Type 2 drivers were introduced for reasons similar to the
Type 1 ODBC bridge driver. 3
Net pure Java drivers
take JDBC requests and translate them into a
network protocol that is not database specific. These requests are s
ent to a server,
which translates the database requests into a database
specific protocol. 4
protocol pure Java drivers
convert JDBC requests to database
network protocols, so that Java programs can connect directly to a database.
Fig. 2
3.26
JDBC driver types.

34. 23.6.2 Querying the books Database
Allow the user to enter any query into the program
Display the results of a query in a JTable

35. 1 // Fig. 23.27: ResultSetTableModel.java
// A TableModel that supplies ResultSet data to a JTable. 3
import java.sql.*;
import java.util.*;
import javax.swing.table.*; 7
// ResultSet rows and columns are counted from 1 and JTable
// rows and columns are counted from 0. When processing
10 // ResultSet rows or columns for use in a JTable, it is
11 // necessary to add 1 to the row or column number to manipulate
12 // the appropriate ResultSet column (i.e., JTable column 0 is
13 // ResultSet column 1 and JTable row 0 is ResultSet row 1).
14 public class ResultSetTableModel extends AbstractTableModel {
private Connection connection;
private Statement statement;
private ResultSet resultSet;
private ResultSetMetaData metaData;
private int numberOfRows; 20
// keep track of database connection status
private boolean connectedToDatabase = false; 23
ResultSetTableModel enables a Jtable to display the contents of a ResultSet.

36. Establishes a connection to the database.
// initialize resultSet and obtain its meta data object;
// determine number of rows
public ResultSetTableModel( String driver, String url,
String query ) throws SQLException, ClassNotFoundException {
// load database driver class
Class.forName( driver ); 31
// connect to database
connection = DriverManager.getConnection( url ); 34
// create Statement to query database
statement = connection.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY ); 39
// update database connection status
connectedToDatabase = true; 42
// set query and execute it
setQuery( query ); } 46
ResultSetTableModel enables a Jtable to display the contents of a ResultSet. Line 33 Lines Line 44
Establishes a connection to the database.
Invokes Connection method createStatement to create a Statement object.
Invokes ResultSetTableModel method setQuery to perform the default query.

37. Obtains the fully qualified class name for the specified column.
// get class that represents column type
public Class getColumnClass( int column ) throws IllegalStateException {
// ensure database connection is available
if ( !connectedToDatabase )
throw new IllegalStateException( "Not Connected to Database" ); 53
// determine Java class of column
try {
String className = metaData.getColumnClassName( column + 1 ); 57
// return Class object that represents className
return Class.forName( className ); } 61
// catch SQLExceptions and ClassNotFoundExceptions
catch ( Exception exception ) {
exception.printStackTrace(); } 66
// if problems occur above, assume type Object
return Object.class; } 70
ResultSetTableModel enables a Jtable to display the contents of a ResultSet. Line 56 Line 59 Line 68
Obtains the fully qualified class name for the specified column.
Loads the class definition for the class and returns the corresponding Class object.
Returns the default type.

38. Obtains the number of columns in the ResultSet.
// get number of columns in ResultSet
public int getColumnCount() throws IllegalStateException {
// ensure database connection is available
if ( !connectedToDatabase )
throw new IllegalStateException( "Not Connected to Database" ); 77
// determine number of columns
try {
return metaData.getColumnCount(); } 82
// catch SQLExceptions and print error message
catch ( SQLException sqlException ) {
sqlException.printStackTrace(); } 87
// if problems occur above, return 0 for number of columns
return 0; } 91
// get name of a particular column in ResultSet
public String getColumnName( int column ) throws IllegalStateException {
// ensure database connection is available
if ( !connectedToDatabase )
throw new IllegalStateException( "Not Connected to Database" );
ResultSetTableModel enables a Jtable to display the contents of a ResultSet. Line 80
Obtains the number of columns in the ResultSet.

39. Obtains the column name from the ResultSet. 98
// determine column name
try {
return metaData.getColumnName( column + 1 ); }
103
// catch SQLExceptions and print error message
catch ( SQLException sqlException ) {
sqlException.printStackTrace(); }
108
// if problems, return empty string for column name
return ""; }
112
// return number of rows in ResultSet
public int getRowCount() throws IllegalStateException {
// ensure database connection is available
if ( !connectedToDatabase )
throw new IllegalStateException( "Not Connected to Database" );
119
return numberOfRows; }
122
Obtains the column name from the ResultSet.
ResultSetTableModel enables a Jtable to display the contents of a ResultSet. Line 101

40. 123 // obtain value in particular row and column
public Object getValueAt( int row, int column )
throws IllegalStateException {
// ensure database connection is available
if ( !connectedToDatabase )
throw new IllegalStateException( "Not Connected to Database" );
130
// obtain a value at specified ResultSet row and column
try {
resultSet.absolute( row + 1 );
134
return resultSet.getObject( column + 1 ); }
137
// catch SQLExceptions and print error message
catch ( SQLException sqlException ) {
sqlException.printStackTrace(); }
142
// if problems, return empty string object
return ""; }
146
ResultSetTableModel enables a Jtable to display the contents of a ResultSet. Line 133 Line 135
Uses ResultSet method absolute to position the ResultSet cursor at a specific row.
Uses ResultSet method getObject to obtain the Object in a specific column of the current row.

41. Executes the query to obtain a new ResultSet.
// set new database query string
public void setQuery( String query )
throws SQLException, IllegalStateException {
// ensure database connection is available
if ( !connectedToDatabase )
throw new IllegalStateException( "Not Connected to Database" );
154
// specify query and execute it
resultSet = statement.executeQuery( query );
157
// obtain meta data for ResultSet
metaData = resultSet.getMetaData();
160
// determine number of rows in ResultSet
resultSet.last(); // move to last row
numberOfRows = resultSet.getRow(); // get row number
164
// notify JTable that model has changed
fireTableStructureChanged(); }
168
ResultSetTableModel enables a Jtable to display the contents of a ResultSet. Line 156 Line 162 Line 163 Line 166
Executes the query to obtain a new ResultSet.
Uses ResultSet method last to position the ResultSet cursor at the last row in the ResultSet.
Uses ResultSet method getRow to obtain the row number for the current row in the ResultSet.
Invokes method fireTableStructureChanged to notify any JTable using this ResultSetTableModel object as its model that the structure of the model has changed.

42. 169 // close Statement and Connection
public void disconnectFromDatabase() {
// close Statement and Connection
try {
statement.close();
connection.close(); }
177
// catch SQLExceptions and print error message
catch ( SQLException sqlException ) {
sqlException.printStackTrace(); }
182
// update database connection status
finally {
connectedToDatabase = false; } }
188
189 } // end class ResultSetTableModel
ResultSetTableModel enables a Jtable to display the contents of a ResultSet. Lines
Close the Statement and Connection if a ResultSetTableModel object is garbage collected.

43. 23.6.2 Querying the books Database (Cont.)

44. 23.6.2 Querying the books Database (Cont.)

45. DisplayQueryResults for querying database books. Lines 15, 16, 19
// Fig : DisplayQueryResults.java
// Display the contents of the Authors table in the
// Books database. 4
import java.awt.*;
import java.awt.event.*;
import java.sql.*;
import java.util.*;
import javax.swing.*;
10 import javax.swing.table.*; 11
12 public class DisplayQueryResults extends JFrame { 13
// JDBC driver and database URL
static final String JDBC_DRIVER = "com.ibm.db2j.jdbc.DB2jDriver";
static final String DATABASE_URL = "jdbc:db2j:books"; 17
// default query selects all rows from authors table
static final String DEFAULT_QUERY = "SELECT * FROM authors"; 20
private ResultSetTableModel tableModel;
private JTextArea queryArea; 23
// create ResultSetTableModel and GUI
public DisplayQueryResults() {
super( "Displaying Query Results" );
DisplayQueryResults for querying database books. Lines 15, 16, 19
Define the database driver class name, database URL and default query.

46. DisplayQueryResults for querying database books. Lines 36-3728
// create ResultSetTableModel and display database table
try { 31
// specify location of database on filesystem
System.setProperty( "db2j.system.home", "C:/Cloudscape_5.0" ); 34
// create TableModel for results of query SELECT * FROM authors
tableModel = new ResultSetTableModel( JDBC_DRIVER, DATABASE_URL,
DEFAULT_QUERY ); 38
// set up JTextArea in which user types queries
queryArea = new JTextArea( DEFAULT_QUERY, 3, 100 );
queryArea.setWrapStyleWord( true );
queryArea.setLineWrap( true ); 43
JScrollPane scrollPane = new JScrollPane( queryArea,
ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER ); 47
// set up JButton for submitting queries
JButton submitButton = new JButton( "Submit Query" ); 50
// create Box to manage placement of queryArea and
// submitButton in GUI
Box box = Box.createHorizontalBox();
box.add( scrollPane );
box.add( submitButton ); 56
DisplayQueryResults for querying database books. Lines 36-37
Create TableModel for results of query SELECT * FROM authors

47. Create JTable delegate for tableModel
JTable resultTable = new JTable( tableModel ); 59
// place GUI components on content pane
Container c = getContentPane();
c.add( box, BorderLayout.NORTH );
c.add( new JScrollPane( resultTable ), BorderLayout.CENTER ); 64
// create event listener for submitButton
submitButton.addActionListener( 67
new ActionListener() { 69
// pass query to table model
public void actionPerformed( ActionEvent event ) {
// perform a new query
try {
tableModel.setQuery( queryArea.getText() ); } 77
// catch SQLExceptions when performing a new query
catch ( SQLException sqlException ) {
JOptionPane.showMessageDialog( null,
sqlException.getMessage(), "Database error",
JOptionPane.ERROR_MESSAGE ); 83
Create JTable delegate for tableModel
DisplayQueryResults for querying database books. Line 58 Lines Line 75
Register an event handler for the submitButton that the user clicks to submit a query to the database.
Invokes ResultSetTableModel method setQuery to execute the new query.

48. DisplayQueryResults for querying database books.
// try to recover from invalid user query
// by executing default query
try {
tableModel.setQuery( DEFAULT_QUERY );
queryArea.setText( DEFAULT_QUERY ); } 90
// catch SQLException when performing default query
catch ( SQLException sqlException2 ) {
JOptionPane.showMessageDialog( null,
sqlException2.getMessage(), "Database error",
JOptionPane.ERROR_MESSAGE ); 96
// ensure database connection is closed
tableModel.disconnectFromDatabase(); 99
System.exit( 1 ); // terminate application
101
} // end inner catch
103
} // end outer catch
105
} // end actionPerformed
107
} // end ActionListener inner class
109
); // end call to addActionListener
111
DisplayQueryResults for querying database books.

49. DisplayQueryResults for querying database books.
// set window size and display window
setSize( 500, 250 );
setVisible( true );
115
} // end try
117
// catch ClassNotFoundException thrown by
// ResultSetTableModel if database driver not found
catch ( ClassNotFoundException classNotFound ) {
JOptionPane.showMessageDialog( null,
"Cloudscape driver not found", "Driver not found",
JOptionPane.ERROR_MESSAGE );
124
System.exit( 1 ); // terminate application
} // end catch
127
// catch SQLException thrown by ResultSetTableModel
// if problems occur while setting up database
// connection and querying database
catch ( SQLException sqlException ) {
JOptionPane.showMessageDialog( null, sqlException.getMessage(),
"Database error", JOptionPane.ERROR_MESSAGE );
134
// ensure database connection is closed
tableModel.disconnectFromDatabase();
137
System.exit( 1 ); // terminate application }
140
DisplayQueryResults for querying database books.

50. DisplayQueryResults for querying database books.
// dispose of window when user quits application (this overrides
// the default of HIDE_ON_CLOSE)
setDefaultCloseOperation( DISPOSE_ON_CLOSE );
144
// ensure database connection is closed when user quits application
addWindowListener(
147
new WindowAdapter() {
149
// disconnect from database and exit when window has closed
public void windowClosed( WindowEvent event ) {
tableModel.disconnectFromDatabase();
System.exit( 0 ); } } );
158
} // end DisplayQueryResults constructor
160
// execute application
public static void main( String args[] ) {
new DisplayQueryResults(); }
166
167 } // end class DisplayQueryResults
DisplayQueryResults for querying database books.

51. DisplayQueryResults for querying database books. Program output

52. Interface CallableStatement
23.7 Stored Procedures
Stored procedures
Store SQL statements in a database
Invoke SQL statements by programs accessing the database
Interface CallableStatement
Receive arguments
Output parameters

53. 23.8 Internet and World Wide Web Resources
Sun Microsystems JDBC home page
Java.sun.com/products/jdbc
SQL materials
Cloudscape database home page