Java Database Connectivity Example

import java.sql.*;

class JavaCon 

{ 

    public static void main(String a[]) 

    { 

        String url = "jdbc:oracle:thin:@localhost:1521:xe"; //connecting to port

        String user = "system"; //user name for dbms

        String pass = "12345";//password

        String sql2 = "select * from STUDENT";

//simple select query Student table already exist in database

        Connection con; //Making connection reference

        try

        { 

            DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());//registering driver 

  

            

            con = DriverManager.getConnection(url,user,pass); //initializing connection object

  

            Statement stm = con.createStatement(); //creating statement object

    System.out.println("Connected");//if all goes well

      ResultSet rs = stm.executeQuery(sql2);

//executing the query which will return whole table as result set

while(rs.next())//row pointer pointing one by one to next row 

{

         //getting attribute values using attribute names

         int roll  = rs.getInt("ROLLNO"); 

         String name = rs.getString("NAME");

         String cl = rs.getString("CLASS");

         System.out.println("NAME: " +name+" Roll Number: "+roll+" CLASS: "+cl);

         

    }

            //closing objects

            rs.close();

            con.close();

            stm.close();

        } 

        catch(Exception e) 

        { 

            System.out.println(e); 

        } 

    } 

} 

Java JDBC Tutorial

JDBC stands for Java Database Connectivity. JDBC is a Java API to connect and execute the query with the database. It is a part of JavaSE (Java Standard Edition). JDBC API uses JDBC drivers to connect with the database. There are four types of JDBC drivers:

JDBC-ODBC Bridge Driver,

Native Driver,

Network Protocol Driver, and

Thin Driver

Driver interface

Connection interface

Statement interface

PreparedStatement interface

CallableStatement interface

ResultSet interface

ResultSetMetaData interface

DatabaseMetaData interface

RowSet interface

A list of popular classes of JDBC API are given below:

DriverManager class

Blob class

Clob class

Types class

Why Should We Use JDBC

Before JDBC, ODBC API was the database API to connect and execute the query with the database. But, ODBC API uses ODBC driver which is written in C language (i.e. platform dependent and unsecured). That is why Java has defined its own API (JDBC API) that uses JDBC drivers (written in Java language).

We can use JDBC API to handle database using Java program and can perform the following activities:

Connect to the database

Execute queries and update statements to the database

Retrieve the result received from the database.Do You Know

How to connect Java application with Oracle and Mysql database using JDBC?

What is the difference between Statement and PreparedStatement interface?

How to print total numbers of tables and views of a database using JDBC?

How to store and retrieve images from Oracle database using JDBC?

How to store and retrieve files from Oracle database using JDBC?

What is API

API (Application programming interface) is a document that contains a description of all the features of a product or software. It represents classes and interfaces that software programs can follow to communicate with each other. An API can be created for applications, libraries, operating systems, etc.

Topics in Java JDBC Tutorial2) JDBC Drivers

In this JDBC tutorial, we will learn four types of JDBC drivers, their advantages and disadvantages.3) 5 Steps to connect to the Database

In this JDBC tutorial, we will see the five steps to connect to the database in Java using JDBC.4) Connectivity with Oracle using JDBC

In this JDBC tutorial, we will connect a simple Java program with the Oracle database.5) Connectivity with MySQL using JDBC

In this JDBC tutorial, we will connect a simple Java program with the MySQL database.6) Connectivity with Access without DSN

Let's connect java application with access database with and without DSN.7) DriverManager class

In this JDBC tutorial, we will learn what does the DriverManager class and what are its methods.8) Connection interface

In this JDBC tutorial, we will learn what is Connection interface and what are its methods.9) Statement interface

In this JDBC tutorial, we will learn what is Statement interface and what are its methods.10) ResultSet interface

In this JDBC tutorial, we will learn what is ResultSet interface and what are its methods. Moreover, we will learn how we can make the ResultSet scrollable.11) PreparedStatement Interface

In this JDBC tutorial, we will learn what is benefit of PreparedStatement over Statement interface. We will see examples to insert, update or delete records using the PreparedStatement interface.12) ResultSetMetaData interface

In this JDBC tutorial, we will learn how we can get the metadata of a table.13) DatabaseMetaData interface

In this JDBC tutorial, we will learn how we can get the metadata of a database.14) Storing image in Oracle

Let's learn how to store image in the Oracle database using JDBC.15) Retrieving image from Oracle

Let's see the simple example to retrieve image from the Oracle database using JDBC.16) Storing file in Oracle

Let's see the simple example to store file in the Oracle database using JDBC.17) Retrieving file from Oracle

Let's see the simple example to retrieve file from the Oracle database using JDBC.18) CallableStatement

Let's see the code to call stored procedures and functions using CallableStatement.19) Transaction Management using JDBC

Let's see the simple example to use transaction management using JDBC.20) Batch Statement using JDBC

Let's see the code to execute batch of queries.21) JDBC RowSet

Let's see the working of new JDBC RowSet interface.

User Defined Exception in JAVA

Although Java’s built-in exceptions handle most common errors, you will probably want

to create your own exception types to handle situations specific to your applications. This

is quite easy to do: just define a subclass of Exception (which is, of course, a subclass of

Throwable). Your subclasses don’t need to actually implement anything—it is their existence

in the type system that allows you to use them as exceptions.

The Exception class does not define any methods of its own. It does, of course, inherit

those methods provided by Throwable. Thus, all exceptions, including those that you create,

have the methods defined by Throwable available to them.Exception defines four constructors. Two were added by JDK 1.4 to support chained

exceptions, described in the next section. The other two are shown here:

Exception( )

Exception(String msg)

The first form creates an exception that has no description. The second form lets you specify

a description of the exception.

Although specifying a description when an exception is created is often useful, sometimes

it is better to override toString( ). Here’s why: The version of toString( ) defined by Throwable

(and inherited by Exception) first displays the name of the exception followed by a colon, which

is then followed by your description. By overriding toString( ), you can prevent the exception

name and colon from being displayed. This makes for a cleaner output, which is desirable in

some cases.

 //User defined exception when radius of circle is negative

class MyException extends Exception

{

MyException()

{

//Empty Constructor must be there

}

MyException(String str)

{

super(str);

}

}

class DemoException

{

static double area(double r) throws MyException

{

if(r<0)

throw new MyException("Radius cannot be negative");

return 3.14*r*r;

}

public static void main(String args[])

{

try

{

System.out.println("Area is "+area(-10.0));

}

catch(MyException e)

{

//e.printStackTrace();

                        System.out.println(e.getMessage());//It will print Radius cannot be negative 

}

finally

{

System.out.println("Inside Finally");

}

System.out.println("Program Ends");

}

}