Getting started with JDBC

Exception handling allows handling exceptional conditions like  program-defined errors in controlled manner.

Program defined error is handled by Exception handling in controlled manner.Exception is thrown when exception condition is caught. Java exception handling and JDBC exception handling are similar.

SQLException Methods:

A SQLException occur both in driver and database. When exception occur object of type SQLException get passed to catch clause.

General Try and Catch Block:-

try {
 // code goes here
}
catch(Exception ex) {
 // exception handling code 
}
finally {
 // it gets executed everytime.
}

import java.sql.*;

public class JDBCExample {
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/USERLOYEE";

   static final String USER_Name = "username";
   static final String PASS = "password1";
   
   public static void main(String[] args) {
   Connection conn1 = null;
   try{
      Class.forName("com.mysql.jdbc.Driver");

      
      Conn1 = DriverManager.getConnection(DB_URL,USER,PASS);

      Statement stmtmnt = conn1.createStatement();
      String sql_1;
      Sql_1 = "SELECT id, first, last, age FROM USER";
      ResultSet rs_1 = stmtmnt.executeQuery(sql_1);

      //STEP 5: data Extract
      while(rs_1.next()){
         //Based on column name retrieve 
         int e_id  = rs_1.getInt("user_id");
         int e_age = rs_1.getInt("user_age");
         String e_first = rs_1.getString("user_first");
         String e_last = rs_1.getString("user_last");

         // values
         System.out.print("user ID: " + user_id);
         System.out.print(",user Age: " + user_age);
         System.out.print(",user First: " + user_first);
         System.out.println(",user Last: " + user_last);
      }
      //release resources
      rs_1.close();
      stmtmnt.close();
      conn1.close();
   }catch(SQLException se){
      // JDBC Handle errors 
      se.printStackTrace();
   }catch(Exception e){
      // Class.forName Handle errors 
      e.printStackTrace();
   }finally{
      // release resources
      try{
         if(conn1!=null)
            conn1.close();
      }catch(SQLException se){
         se.printStackTrace();
      }
     }
   }
}

Compile and run above example as follows:

C:\>javac ExampleJDBC.java

C:\>java ExampleJDBC 

user ID: 100, user Age: 5, user First: Yuvraaj, user Last: C

user ID: 101, user Age: 2, user First: Nimrit, user Last: K