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The Basic Steps to Connect Oracle and Java Program
Here, I will show you what the steps to make a connection between Oracle
database and your Java program. To do this work, you need the JDBC (Java
DataBase Connectivity) driver. The file name of Oracle's JDBC driver is
classes12.zip or classes12.jar. By default, Oracle have included this driver at
the software installation process. Its location is in the ORACLE_HOME\jdbc\lib
directory. For example, if our ORACLE_HOME is C:\Oracle\Ora90 then the JDBC
driver will be placed in C:\Oracle\Ora90\jdbc\lib directory.
Make sure to set the Java CLASSPATH correctly. Here is the command line to do
it.
(Note: Assume the ORACLE_HOME is C:\Oracle\Ora90)
set CLASSPATH=.;C:\Oracle\Ora90\jdbc\lib\classes12.jar
or
set CLASSPATH=.;C:\Oracle\Ora90\jdbc\lib\classes12.zip
In addition, you can also set the CLASSPATH in your autoexec.bat file on your
Windows operating system.
Now, just follow these steps:
STEP 1. Import the java.sql package into your program.
------------------------------------------------------
import java.sql.*;
The syntax above will import all classes in the java.sql package. If you want to
import a few of them, you can write the syntax like this
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.Connection;
It only imports the Driver, DriverManager, and Connection class into your Java
program.
STEP 2. Load the Oracle's JDBC driver.
--------------------------------------
There are two ways to load your JDBC driver. The first, use the forName() method
of java.lang.Class class.
Class.forName("oracle.jdbc.driver.OracleDriver");
And the second way is use the registerDriver() method of DriverManager class.
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
STEP 3. Create a Connection object.
-----------------------------------
To create a Connection object, use the getConnection() method of DriverManager
class. This method takes three parameters: URL, username, and password.
Connection conn =
DriverManager.getConnection(
"jdbc:oracle:thin:@mylaptop:1521:ORADB", // URL
"budiraharjo", // username
"SDDNBandung" // password
);
STEP 4. Create a Statement object.
----------------------------------
The Statement object can be created by call the createStatement() method of
Connection object that you made before. So, you can write the following code
Statement mystat = conn.createStatement();
STEP 5. Execute your SQL statement.
-----------------------------------
After you create a Statement object successfully, you can execute a query
(SELECT statement) from your Java program using the executeQuery() method of
Statement class. The result of execution process will be stored in ResultSet
object, so you need to declare an object of ResultSet first. Here is the code.
ResultSet rs = mystat.executeQuery("select custno, custname from customer");
STEP 6. Display your data.
--------------------------
The next step is display your data using the looping control.
while (rs.next()) {
System.out.println(
rs.getInt(1) + // first column
"\t" + // the horizontal tab
rs.getString(2) // second column
);
}
STEP 7. Close your statement and connection.
--------------------------------------------
mystat.close();
conn.close();
Here is the complete code.
/*********************************************************************
* File name : SimpleOraJava.java
* Author : Budi Raharjo (PT. Sigma Delta Duta Nusantara, Bandung)
* Blog :
http://mbraharjo.blogspot.com
*
*********************************************************************/
import java.sql.*;
class SimpleOraJava {
public static void main(String args[]) throws SQLException {
DriverManager.registerDriver(
new oracle.jdbc.driver.OracleDriver()
);
String serverName = "mylaptop";
int port = 1521;
String user = "budi";
String password = "SDDNBandung";
String SID = "ORADB";
String URL = "jdbc:oracle:thin:@" + serverName + ":" + port + ":" + SID;
Connection conn = DriverManager.getConnection(URL, user, password);
String SQL = "SELECT CUSTNO, CUSTNAME FROM CUSTOMER";
Statement stat = conn.createStatement();
ResultSet rs = stat.executeQuery(SQL);
while (rs.next()) {
System.out.println(
rs.getInt(1) +
"\t" +
rs.getString(2)
);
}
stat.close();
conn.close();
}
}
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