JDBC Statement Object Example

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Following is the example which makes use of following three queries along with opening and closing statment:

  1. boolean execute(String SQL) : Returns a boolean value of true if a ResultSet object can be retrieved; otherwise, it returns false. Use this method to execute SQL DDL statements or when you need to use truly dynamic SQL.

  2. int executeUpdate(String SQL) : Returns the numbers of rows affected by the execution of the SQL statement. Use this method to execute SQL statements for which you expect to get a number of rows affected - for example, an INSERT, UPDATE, or DELETE statement.

  3. ResultSet executeQuery(String SQL) : Returns a ResultSet object. Use this method when you expect to get a result set, as you would with a SELECT statement.

This sample code was written based on the environment and database setup done in previous chapters.

Copy and paste below code in example.java, compile and run:


//STEP 1. Import required packages
import java.sql.*;
public class example {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/EMP";
   //  Database credentials
   static final String USER = "username";
   static final String PASS = "password";
   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
      //STEP 2: Register JDBC driver
      //STEP 3: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL,USER,PASS);
      //STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();
      String sql = "UPDATE Friends set age=24 WHERE id=103";
        // Let us check if it returns a true Result Set or not.
      Boolean ret = stmt.execute(sql);
      System.out.println("Return value is : " + ret.toString() );
      // Let us update age of the record with ID = 103;
      int rows = stmt.executeUpdate(sql);
      System.out.println("Rows impacted : " + rows );
      // Let us select all the records and display them.
      sql = "SELECT id, first, last, age FROM Friends";
      ResultSet rs = stmt.executeQuery(sql);
      //STEP 5: Extract data from result set
         //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);
      //STEP 6: Clean-up environment
   }catch(SQLException se){
      //Handle errors for JDBC
   }catch(Exception e){
      //Handle errors for Class.forName
      //finally block used to close resources
      }catch(SQLException se2){
      }// nothing we can do
      }catch(SQLException se){
      }//end finally try
   }//end try
   System.out.println("Have A Nice Day");
}//end main
}//end example

Now compile above example:


C:\>javac example.java


C:\>java example
Connecting to database...
Creating statement...
Return value is : false
Rows impacted : 1
ID: 100, Age: 21, First: Sophia, Last: Lomela
ID: 101, Age: 23, First: Katrina, Last: Kane
ID: 102, Age: 24, First: Guru, Last: Morkel
ID: 103, Age: 24, First: Simone, Last: Washer
Have A Nice Day

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