Getting Started with Java and Jdbc

Introduction

JDBC offers a database independent interface to connect to various SQL databases. It's similar to Perl DBI.

Typical JDBC Program

A typical JDBC Program looks like this 
import java.sql.*;

public class connect {
    public static void main(String args[]) {
        String url = "jdbc:oracle:thin:@oracle:1521:cen3031";

        // Load the oracle driver
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
        }
        catch (Exception e) {
            System.out.println("Failed to load oracle driver");
            System.out.println(e.toString());
            System.exit(1);
        }

        try {
            // Make a connection handle to the database
            Connection con = DriverManager.getConnection(url, "ppadala", "******");

            // Prepare and execute a statement
            Statement st = con.createStatement();
            ResultSet result = st.executeQuery("select * from oraclehw");
            
            System.out.println("Results");

            // Display the results
            while(result.next()) {
                System.out.println("name = " + result.getString(1));
                System.out.println("email = " + result.getString(2));
            }

            // Release the resources for connection
            st.close();
            con.close();
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    }
}

The comments pretty much explain the program. It follows the same pattern described in the Database Programming tutorial.

Compiling the program

To compile the program, set ORACLE_HOME and CLASSPATH with 

    source /usr/local/etc/ora.csh
    setenv CLASSPATH ${CLASSPATH}:${ORACLE_HOME}/jdbc/lib/classes12.zip

Compile the program with javac 

    javac <java source>

Executing the program

Execute the class file as 

    java <class name>

If you get an error like 

    rain% java connect
    Failed to load oracle driver
    java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
Make sure that you set the classpath properly. Execute these programs on CISE main servers rain and sand only.

Sample Output

Output from above program may look like 
rain:19% java connect
Results
-------
name = rte email = rt
name = robert email = rmc@cise.ufl.edu
name = banana email = abc@banana.com
name = Pradeep Padala email = abc@bbc.com
name = banana email = abc@banana.com
Maintained by Pradeep Padala