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Wednesday, 7 January 2015

Connectivity with Access without DSN

There are two ways to connect java application with the access database.

  1. Without DSN (Data Source Name)
  2. With DSN
Java is mostly used with Oracle, mysql, or DB2 database. So you can learn this topic only for knowledge.

Example to Connect Java Application with access without DSN

In this example, we are going to connect the java program with the access database. In such case, we have created the login table in the access database. There is only one column in the table named name. Let's get all the name of the login table.
  1. import java.sql.*;  
  2. class Test{  
  3. public static void main(String ar[]){  
  4.  try{  
  5.    String database="student.mdb";//Here database exists in the current directory  
  6.   
  7.    String url="jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};  
  8.                     DBQ=" + database + ";DriverID=22;READONLY=true";  
  9.   
  10.    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  
  11.    Connection c=DriverManager.getConnection(url);  
  12.    Statement st=c.createStatement();  
  13.    ResultSet rs=st.executeQuery("select * from login");  
  14.     
  15.    while(rs.next()){  
  16.     System.out.println(rs.getString(1));  
  17.    }  
  18.   
  19. }catch(Exception ee){System.out.println(ee);}  
  20.   
  21. }}  

Example to Connect Java Application with access with DSN

Connectivity with type1 driver is not considered good. To connect java application with type1 driver, create DSN first, here we are assuming your dsn name is mydsn.
  1. import java.sql.*;  
  2. class Test{  
  3. public static void main(String ar[]){  
  4.  try{  
  5.    String url="jdbc:odbc:mydsn";  
  6.    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  
  7.    Connection c=DriverManager.getConnection(url);  
  8.    Statement st=c.createStatement();  
  9.    ResultSet rs=st.executeQuery("select * from login");  
  10.     
  11.    while(rs.next()){  
  12.     System.out.println(rs.getString(1));  
  13.    }  
  14.   
  15. }catch(Exception ee){System.out.println(ee);}  
  16.   
  17. }}  

Tuesday, 6 January 2015

Connectivity with MySQL

For connecting java application with the mysql database, you need to follow 5 steps to perform database connectivity.

In this example we are using MySql as the database. So we need to know following informations for the mysql database:
  1. Driver class: The driver class for the mysql database is com.mysql.jdbc.Driver.
  2. Connection URL: The connection URL for the mysql database is jdbc:mysql://localhost:3306/sonoo where jdbc is the API, mysql is the database, localhost is the server name on which mysql is running, we may also use IP address, 3306 is the port number and sonoo is the database name. We may use any database, in such case, you need to replace the sonoo with your database name.
  3. Username: The default username for the mysql database is root.
  4. Password: Password is given by the user at the time of installing the mysql database. In this example, we are going to use root as the password.
Let's first create a table in the mysql database, but before creating table, we need to create database first.
  1. create database sonoo;  
  2. use sonoo;  
  3. create table emp(id int(10),name varchar(40),age int(3));  

Example to Connect Java Application with mysql database

In this example, sonoo is the database name, root is the username and password.
  1. import java.sql.*;  
  2. class MysqlCon{  
  3. public static void main(String args[]){  
  4. try{  
  5. Class.forName("com.mysql.jdbc.Driver");  
  6.   
  7. Connection con=DriverManager.getConnection(  
  8. "jdbc:mysql://localhost:3306/sonoo","root","root");  
  9.   
  10. //here sonoo is database name, root is username and password  
  11.   
  12. Statement stmt=con.createStatement();  
  13.   
  14. ResultSet rs=stmt.executeQuery("select * from emp");  
  15.   
  16. while(rs.next())  
  17. System.out.println(rs.getInt(1)+"  "+rs.getString(2)+"  "+rs.getString(3));  
  18.   
  19. con.close();  
  20.   
  21. }catch(Exception e){ System.out.println(e);}  
  22.   
  23. }  
  24. }  
The above example will fetch all the records of emp table.

To connect java application with the mysql database mysqlconnector.jar file is required to be loaded.

Two ways to load the jar file:

  1. paste the mysqlconnector.jar file in jre/lib/ext folder
  2. set classpath

1) paste the mysqlconnector.jar file in JRE/lib/ext folder:

Download the mysqlconnector.jar file. Go to jre/lib/ext folder and paste the jar file here.

2) set classpath:

There are two ways to set the classpath:
  • temporary
  • permament

How to set the temporary classpath

open comman prompt and write:
  1. C:>set classpath=c:\folder\mysql-connector-java-5.0.8-bin.jar;.;  

How to set the permanent classpath

Go to environment variable then click on new tab. In variable name write classpath and in variable value paste the path to the mysqlconnector.jar file by appending mysqlconnector.jar;.; as C:\folder\mysql-connector-java-5.0.8-bin.jar;.;

Monday, 5 January 2015

Connectivity with Oracle


For connecting java application with the oracle database, you need to follow 5 steps to perform database connectivity. In this example we are using Oracle10g as the database. So we need to know following informations for the oracle database:
  1. Driver class: The driver class for the oracle database is oracle.jdbc.driver.OracleDriver.
  2. Connection URL: The connection URL for the oracle10G database is jdbc:oracle:thin:@localhost:1521:xe where jdbc is the API, oracle is the database, thin is the driver, localhost is the server name on which oracle is running, we may also use IP address, 1521 is the port number and XE is the Oracle service name. You may get all these informations from the tnsnames.ora file.
  3. Username: The default username for the oracle database is system.
  4. Password: Password is given by the user at the time of installing the oracle database.

Let's first create a table in oracle database.
  1. create table emp(id number(10),name varchar2(40),age number(3));  

Example to Connect Java Application with Oracle database

In this example, system is the username and oracle is the password of the Oracle database.
  1. import java.sql.*;  
  2. class OracleCon{  
  3. public static void main(String args[]){  
  4. try{  
  5. //step1 load the driver class  
  6. Class.forName("oracle.jdbc.driver.OracleDriver");  
  7.   
  8. //step2 create  the connection object  
  9. Connection con=DriverManager.getConnection(  
  10. "jdbc:oracle:thin:@localhost:1521:xe","system","oracle");  
  11.   
  12. //step3 create the statement object  
  13. Statement stmt=con.createStatement();  
  14.   
  15. //step4 execute query  
  16. ResultSet rs=stmt.executeQuery("select * from emp");  
  17. while(rs.next())  
  18. System.out.println(rs.getInt(1)+"  "+rs.getString(2)+"  "+rs.getString(3));  
  19.   
  20. //step5 close the connection object  
  21. con.close();  
  22.   
  23. }catch(Exception e){ System.out.println(e);}  
  24.   
  25. }  
  26. }  
The above example will fetch all the records of emp table.

To connect java application with the Oracle database ojdbc14.jar file is required to be loaded.

Two ways to load the jar file:

  1. paste the ojdbc14.jar file in jre/lib/ext folder
  2. set classpath

1) paste the ojdbc14.jar file in JRE/lib/ext folder:

Firstly, search the ojdbc14.jar file then go to JRE/lib/ext folder and paste the jar file here.

2) set classpath:

There are two ways to set the classpath:
  • temporary
  • permanent

How to set the temporary classpath:

Firstly, search the ojdbc14.jar file then open command prompt and write:
  1. C:>set classpath=c:\folder\ojdbc14.jar;.;  

How to set the permanent classpath:

Go to environment variable then click on new tab. In variable name write classpath and in variable value paste the path to ojdbc14.jar by appending ojdbc14.jar;.; as C:\oraclexe\app\oracle\product\10.2.0\server\jdbc\lib\ojdbc14.jar;.;

Sunday, 4 January 2015

5 Steps to connect to the database in java

There are 5 steps to connect any java application with the database in java using JDBC. They are as follows:
  • Register the driver class
  • Creating connection
  • Creating statement
  • Executing queries
  • Closing connection

1) Register the driver class

The forName() method of Class class is used to register the driver class. This method is used to dynamically load the driver class.

Syntax of forName() method

  1. public static void forName(String className)throws ClassNotFoundException  

Example to register the OracleDriver class

  1. Class.forName("oracle.jdbc.driver.OracleDriver");  

2) Create the connection object

The getConnection() method of DriverManager class is used to establish connection with the database.

Syntax of getConnection() method

  1. 1public static Connection getConnection(String url)throws SQLException  
  2. 2public static Connection getConnection(String url,String name,String password)  
  3. throws SQLException  

Example to establish connection with the Oracle database

  1. Connection con=DriverManager.getConnection(  
  2. "jdbc:oracle:thin:@localhost:1521:xe","system","password");  

3) Create the Statement object

The createStatement() method of Connection interface is used to create statement. The object of statement is responsible to execute queries with the database.

Syntax of createStatement() method

  1. public Statement createStatement()throws SQLException  

Example to create the statement object

  1. Statement stmt=con.createStatement();  

4) Execute the query

The executeQuery() method of Statement interface is used to execute queries to the database. This method returns the object of ResultSet that can be used to get all the records of a table.

Syntax of executeQuery() method

  1. public ResultSet executeQuery(String sql)throws SQLException  

Example to execute query

  1. ResultSet rs=stmt.executeQuery("select * from emp");  
  2.   
  3. while(rs.next()){  
  4. System.out.println(rs.getInt(1)+" "+rs.getString(2));  
  5. }  

5) Close the connection object

By closing connection object statement and ResultSet will be closed automatically. The close() method of Connection interface is used to close the connection.

Syntax of close() method

  1. public void close()throws SQLException  

Example to close connection


  1. con.close();  

Saturday, 3 January 2015

JDBC Driver

JDBC Driver is a software component that enables java application to interact with the database.There are 4 types of JDBC drivers:
  1. JDBC-ODBC bridge driver
  2. Native-API driver (partially java driver)
  3. Network Protocol driver (fully java driver)
  4. Thin driver (fully java driver)

1) JDBC-ODBC bridge driver

The JDBC-ODBC bridge driver uses ODBC driver to connect to the database. The JDBC-ODBC bridge driver converts JDBC method calls into the ODBC function calls. This is now discouraged because of thin driver.
bridge driver

Advantages:

  • easy to use.
  • can be easily connected to any database.

Disadvantages:

  • Performance degraded because JDBC method call is converted into the ODBC function calls.
  • The ODBC driver needs to be installed on the client machine.

2) Native-API driver

The Native API driver uses the client-side libraries of the database. The driver converts JDBC method calls into native calls of the database API. It is not written entirely in java.
Native-API driver

Advantage:

  • performance upgraded than JDBC-ODBC bridge driver.

Disadvantage:

  • The Native driver needs to be installed on the each client machine.
  • The Vendor client library needs to be installed on client machine.

3) Network Protocol driver

The Network Protocol driver uses middleware (application server) that converts JDBC calls directly or indirectly into the vendor-specific database protocol. It is fully written in java.
Network Protocol driver

Advantage:

  • No client side library is required because of application server that can perform many tasks like auditing, load balancing, logging etc.

Disadvantages:

  • Network support is required on client machine.
  • Requires database-specific coding to be done in the middle tier.
  • Maintenance of Network Protocol driver becomes costly because it requires database-specific coding to be done in the middle tier.

4) Thin driver

The thin driver converts JDBC calls directly into the vendor-specific database protocol. That is why it is known as thin driver. It is fully written in Java language.
Thin driver

Advantage:

  • Better performance than all other drivers.
  • No software is required at client side or server side.

Disadvantage:

  • Drivers depends on the Database.

Friday, 2 January 2015

Java JDBC

Java JDBC is a java API to connect and execute query with the database. JDBC API uses jdbc drivers to connect with the database.

JDBC (Java Database Connectivity)

Why use JDBC

Before JDBC, ODBC API was the database API to connect and execute 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).
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 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