imranhsayed / programming-in-java

Example programs in Java

programming-in-java

Example programs in Java

What is ResultSet In Java?

• ResultSet is an interface in Java that is used to get the database result in a table format.
• The object of ResultSet maintains a cursor pointing to a row of a table. Initially, cursor points to before the first row.
• But we can make this object to move forward and backward direction by passing either TYPE_SCROLL_INSENSITIVE or TYPE_SCROLL_SENSITIVE in createStatement(int,int) method as well as we can make this object as updatable by:

Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,  
                     ResultSet.CONCUR_UPDATABLE);  

• Example

import java.sql.*;  
class FetchRecord{  
public static void main(String args[])throws Exception{  
  
Class.forName("oracle.jdbc.driver.OracleDriver");  
Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","system","oracle");  
Statement stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);  
ResultSet rs=stmt.executeQuery("select * from emp765");  
  
//getting the record of 3rd row  
rs.absolute(3);  
System.out.println(rs.getString(1)+" "+rs.getString(2)+" "+rs.getString(3));  
  
con.close();  
}}  

• Another example

/STEP 1. Import required packages
import java.sql.*;

public class Main{
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/STUDENTS";

   //  Database credentials
   static final String USER = "username";
   static final String PASS = "password";
   
   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //STEP 2: Register JDBC driver
      Class.forName("com.mysql.jdbc.Driver");

      //STEP 3: Open a connection
      System.out.println("Connecting to a selected database...");
      conn = DriverManager.getConnection(DB_URL, USER, PASS);
      System.out.println("Connected database successfully...");
      
      //STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();

      String sql = "SELECT id, first, last, age FROM Registration";
      ResultSet rs = stmt.executeQuery(sql);
      //STEP 5: Extract data from result set
      while(rs.next()){
         //Retrieve by column name
         int id  = rs.getInt("id");
         int age = rs.getInt("age");
         String first = rs.getString("first");
         String last = rs.getString("last");

         //Display values
         System.out.print("ID: " + id);
         System.out.print(", Age: " + age);
         System.out.print(", First: " + first);
         System.out.println(", Last: " + last);
      }
      rs.close();
   }catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();
   }catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
   }finally{
      //finally block used to close resources
      try{
         if(stmt!=null)
            conn.close();
      }catch(SQLException se){
      }// do nothing
      try{
         if(conn!=null)
            conn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }//end finally try
   }//end try
   System.out.println("Goodbye!");
}//end main
}//end Class