Download An Introduction to Java Database Connectivity (JDBC)

CS6401
An Introduction to Java Database Connectivity (JDBC)
Tuesday 5 October 2010
RECAP...
• Looked
at evolution and uses of databases
• Introduced
n-tier design architecture
• Introduced
the problem area for our programme
Tuesday 5 October 2010
STRUCTURE OF TODAY’S PROGRAM
Our Code
1-Tier Program with a single
operation (a select)
JAVA GENERIC JDBC
Vendor JDBC Driver
Database
Tuesday 5 October 2010
OUR TOOLS TODAY
• MySQL
Query Browser - available at: http://dev.mysql.com/downloads/guitools/5.0.html but migrating to MySQL Workbench.
• MySQL
JDBC Driver
• Console
compilation, Java Runtime Environment (JRE), and Editor (swap in
your favorite IDE...)
Tuesday 5 October 2010
MYSQL QUERY BROWSER
Tuesday 5 October 2010
COMPONENTS OF OUR PROGRAM
• Import
statements
• Connection
• Loading
• Creating
the appropriate driver and creating a connection
a statement and executing a query
• Processing
Tuesday 5 October 2010
String
the returned result set
IMPORT STATEMENTS
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import com.mysql.jdbc.Driver;
The final one is part of MySQL’s JDBC jar file available at:
http://dev.mysql.com/usingmysql/java/
Tuesday 5 October 2010
CONNECTION STRING (13)
private final String CONNECTION_STRING = "jdbc:mysql://cosmos.ucc.ie:
3306/database_name?user=db_username&password=db_password";
Need to know:
1. The server and port on which the database management system runs
II. The name of the database to which you want to connect to
III. The username with which to connect
IV. The password for that username
Tuesday 5 October 2010
DRIVER AND CONNECTION
java.sql.DriverManager.registerDriver(new Driver());
java.sql.Connection con = DriverManager.getConnection(CONNECTION_STRING);
1. We load the appropriate driver - vendor specific code that interfaces with Java’s
generic database hander
II. We imported the MySQL driver earlier - now we register that as the object Java
will talk to in-order to fulfill requests
III. We create a connection with the database defined in the connection string
Tuesday 5 October 2010
CREATE/EXECUTE A STATEMENT
(32,34)
java.sql.Statement stmt = con.createStatement();
java.sql.ResultSet rs = stmt.executeQuery("SELECT * FROM photos");
1. The connection provides us with a statement object that understands how to
execute SQL
II. We provide the SQL, and the statement takes care of the rest, returning a
ResultSet (set of objects representing returned rows from the DB)
Tuesday 5 October 2010
PROCESS RESULTS
while(rs.next()){
System.out.println(rs.getString(1) + “ “ + rs.getString(2) + “ “ + rs.getString(3)
+ “ “ rs.getString(4) + “ “ + rs.getString(5) + “\n”);
}
1. For each object in the resultset (representing a pointer to a matching row
in the table) print out the values of the attributes separated by spaces
Tuesday 5 October 2010
PROCESS RESULTS (41-45)
while(rs.next()){
System.out.println(rs.getString(“photoid”) + “\n”);
}
1. Could also use attribute names to access values, can have any order
Tuesday 5 October 2010