Java queries Pro

What is single member annotation and how to process it

package com.java2novice.annotations;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.reflect.Method;

Retention(RetentionPolicy.Runtime)

interface MyAnnotn

{

    String value();

}

public class MySingleMembAnnotation

{

   MyAnnotn("java2novice.com")

    public void myAnnotationTestMethod()

   {

    try

    {

            Class MySingleMembAnnotation> cls = this.getClass();

            Method mth = cls.getMethod("myAnnotationTestMethod");

            MyAnnotn myAnno = mth.getAnnotation(MyAnnotn.class);

            System.out.println("value: "+myAnno.value());

        }

         catch (SecurityException e)

         {

            e.printStackTrace();

         }

         catch (NoSuchMethodException e)

         {

                     e.printStackTrace();

        }

    }

     

    public static void main(String a[])

    {

        MySingleMembAnnotation mat = new MySingleMembAnnotation();

        mat.myAnnotationTestMethod();

    }

}

How to create JDBC Connection

package com.java2novice.jdbc;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.SQLException;

import java.sql.Statement;

public class JdbcConnection

{

public static void main(String a[])

{

       try

      {

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

            Connection con = DriverManager.

                getConnection("jdbc:oracle:thin:::"

                    ,"user","password");

            Statement stmt = con.createStatement();

            System.out.println("Created DB Connection....");

        }

         catch (ClassNotFoundException e)

        {

            e.printStackTrace();

        }

         catch (SQLException e)

        {

            e.printStackTrace();

        }

    }

}

How to execute and read select queries using JDBC

package com.java2novice.jdbc;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class MyResultSetEx

{

public static void main(String a[])

{

    try

   {

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

            Connection con = DriverManager

           .getConnection("jdbc:oracle:thin:::","user","password");

            Statement stmt = con.createStatement();

            System.out.println("Created DB Connection....");

            ResultSet rs = stmt.executeQuery("select name, salary from emp");

            while(rs.next())

            {

                System.out.println(rs.getString("name"));

                System.out.println(rs.getInt("salary"));

            }

            rs.close();

            con.close();

        }

         catch (ClassNotFoundException e)

         {

          e.printStackTrace();

          }

          catch (SQLException e)

          {

                      e.printStackTrace();

           }

    }

}

How to update a record in the database using JDBC

package com.java2novice.jdbc;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.SQLException;

import java.sql.Statement;

public class MyQueryUpdate

{

 public static void main(String[] args)

{

        Connection con = null;

        Statement stmt = null;

        try

      {

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

            con = DriverManager.

        getConnection("jdbc:oracle:thin:::"

         ,"user","password");

            stmt = con.createStatement();

            String query = "update table emp set salary=2000 where empid=200";

             int count = stmt.executeUpdate(query);

            System.out.println("Updated queries: "+count);

        }

         catch (ClassNotFoundException e)

         {

          e.printStackTrace();

         }

         catch (SQLException e)

         {

                     e.printStackTrace();

        }  

         finally

         {

            try

             {

                if(stmt != null) stmt.close();

                if(con != null) con.close();

            }

            catch(Exception ex){}

        }

    }

}

How to execute any type of query in JDBC

package com.java2novice.jdbc;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class MyExecuteMethod

{

public static void main(String a[])

{

        Connection con = null;

        try

      {

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

            con = DriverManager.

                    getConnection("jdbc:oracle:thin:@::"

                        ,"user","password");

            Statement stmt = con.createStatement();

            String query = "select * from emp";

            boolean status = stmt.execute(query);

            if(status)

            {

                ResultSet rs = stmt.getResultSet();

                while(rs.next())

               {

                    System.out.println(rs.getString(1));

                }

                rs.close();

            }

            else

         {

                int count = stmt.getUpdateCount();

                System.out.println("Total records updated: "+count);

            }

        }

         catch (ClassNotFoundException e)

         {

          e.printStackTrace();

          }

          catch (SQLException e)

          {

            e.printStackTrace();

        }

         finally

         {

            try

            {

                if(con != null) con.close();

            }

            catch (Exception ex){}

        }

    }

}