¿Cómo enviar una consulta en JDBC?

Java

// importing the my sql package
import java.sql.*;
 
/* The below code cannot generate the output here, since
 * there is no connection between client and mysql server
 *
 * Before running the project in your device
 * make SQL server connection with your project
 
 * create the respective database/table in sql server
 * in URL write the port number in which your mysql server
 * is running (By default it run in port number 3306)
 */
 
public class GFG {
 
    public static void main(String[] args)
    {
        // Database name
        String databaseName = "student";
 
        // Database URL
        String url
            = "jdbc:mysql://localhost:3306/" + databaseName;
 
        // Database credentials
        String userName = "root";
        String password = "root";
 
        Connection con = null;
        Statement st = null;
        ResultSet res = null;
        String query = "";
 
        try {
 
            // Register the jdbc driver
            Class.forName("com.mysql.jdbc.Driver");
 
            // open a connection to database
            con = DriverManager.getConnection(url, userName,
                                              password);
 
            // set auto commit false
            con.setAutoCommit(false);
 
            // creating statement
            st = con.createStatement();
 
            // first let us try to understand , how DB works
            //  without commit statement
            query
                = "INSERT INTO Student values ( 11 , 'Ram' , 'banglore' )";
 
            // executing query 1 -> adding the above
            // information into the table
            st.executeUpdate(query);
            System.out.println(
                "Inserted row 1 FIRST TIME in the table....");
 
            query
                = "INSERT INTO Student values ( 22 , 'Shyam' , 'Chennai' )";
            st.executeUpdate(query);
            System.out.println(
                "Inserted row 2 FIRST TIME in the table....");
 
            // lets , print what we have updated in the table
            query = "Select * from Student ; ";
            res = st.executeQuery(query);
 
            System.out.println(
                "printing data (without Rollback && without Commit )....");
 
            while (res.next())
                System.out.print(res.getString("name")
                                 + "   ");
            System.out.println();
 
            // lets try to rollback (undo the things ,till now we did)
            // see what difference it will make in the Database
            con.rollback();
 
            // lets checkout our DB again
            query = "Select * from Student";
            res = st.executeQuery(query);
 
            System.out.println(
                "printing data (with Rollback && without Commit )....");
            boolean empty = true;
 
            while (res.next()) {
                empty = false;
                System.out.print(res.getString("name")
                                 + "  ");
            }
            if (empty) {
                System.out.println("Empty table\n\n");
            }
 
            // Since we haven't committed our transaction ,
            // when we did rollback, everything is gone
            // Now lets ,try with the Commit Statement from
            // beginning
            query
                = "INSERT INTO Student values ( 11 , 'Ram' , 'banglore' )";
            st.executeUpdate(query);
            System.out.println(
                "Inserted row 1  SECOND TIME in the table....");
 
            query
                = "INSERT INTO Student values ( 22 , 'Shyam' , 'Chennai' )";
            st.executeUpdate(query);
            System.out.println(
                "Inserted row 2  SECOND TIME in the table....");
 
            // now we have committed our transaction
            con.commit();
            System.out.println(
                "committed the transaction successfully....");
 
            // lets rollback  and like previous lets check
            // what will be left in our database
            con.rollback();
            System.out.println("Done Rollback....");
 
            query = "Select * from Student";
            res = st.executeQuery(query);
 
            System.out.println(
                "printing data ( with Commit and then Rollback)....");
 
            while (res.next())
                System.out.print(res.getString("name")
                                 + "   ");
 
            System.out.println("\n");
        }
        catch (ClassNotFoundException e) {
            System.out.println("Driver Error");
            e.printStackTrace();
        }
        catch (SQLException e) {
            System.out.println("Connection Error");
            e.printStackTrace();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
 
        try {
 
            // Clean-up environment
            if (con != null)
                con.close();
            if (st != null)
                con.close();
            if (res != null)
                res.close();
        }
        catch (Exception e) {
 
            // Handle errors for JDBC
            System.out.println(e.getMessage());
        }
        finally {
            System.out.println("Thank you .........");
        }
    }
}