connect database - class MyConnect

package nguyenvanquan7826.database;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class MyConnect {

    private final String className = "com.mysql.jdbc.Driver";
    private final String url = "jdbc:mysql://localhost:3306/student";
    private final String user = "root";
    private final String pass = "lamgicopass";

    private String table = "student_info";

    private Connection connection;

    // connect to database
    public void connect() {
        try {
            Class.forName(className);
            connection = DriverManager.getConnection(url, user, pass);
            System.out.println("Connect success!");
        } catch (ClassNotFoundException e) {
            System.out.println("Class not found!");
        } catch (SQLException e) {
            System.out.println("Error connection!");
        }
    }

    // show data is selected
    public void showData(ResultSet rs) {
        try {
            while (rs.next()) {
                System.out.printf("%-10s %-20s %-5.2f \n", rs.getString(1),
                        rs.getString(2), rs.getDouble(3));
            }
        } catch (SQLException e) {
        }
    }

    // get data and return Resultset with command select
    public ResultSet getData() {
        ResultSet rs = null;
        String sqlCommand = "select * from " + table;
        Statement st;
        try {
            st = connection.createStatement();
            rs = st.executeQuery(sqlCommand);
        } catch (SQLException e) {
            System.out.println("select error \n" + e.toString());
        }
        return rs;
    }

    // get data and return Resultset with command select by Id
    public ResultSet getDataId(String id) {
        ResultSet rs = null;
        String sqlCommand = "select * from " + table + " where id = ?";
        PreparedStatement pst = null;
        try {
            pst = connection.prepareStatement(sqlCommand);
            // replace "?" by id
            pst.setString(1, id);
            rs = pst.executeQuery();
        } catch (SQLException e) {
            System.out.println("select error \n" + e.toString());
        }
        return rs;
    }

    // delete by Id
    public void deleteId(String id) {
        String sqlCommand = "delete from " + table + " where id = ?";
        PreparedStatement pst = null;
        try {
            pst = connection.prepareStatement(sqlCommand);
            pst.setString(1, id);
            if (pst.executeUpdate() > 0) {
                System.out.println("delete success");
            } else {
                System.out.println("delete error \n");
            }
        } catch (SQLException e) {
            System.out.println("delete error \n" + e.toString());
        }
    }

    // insert student s to database
    public void insert(Student s) {
        String sqlCommand = "insert into " + table + " value(?, ?, ?)";
        PreparedStatement pst = null;
        try {
            pst = connection.prepareStatement(sqlCommand);
            // replace three "?" by id, Name and point of Studnet s
            pst.setString(1, s.getId());
            pst.setString(2, s.getName());
            pst.setDouble(3, s.getPoint());
            if (pst.executeUpdate() > 0) {
                System.out.println("insert success");
            } else {
                System.out.println("insert error \n");
            }
        } catch (SQLException e) {
            System.out.println("insert error \n" + e.toString());
        }
    }

    // update studetn by Id
    public void updateId(String id, Student s) {
        String sqlCommand = "update " + table
                + " set name = ?, point = ? where id = ?";
        PreparedStatement pst = null;
        try {
            pst = connection.prepareStatement(sqlCommand);
            pst.setString(1, s.getName());
            pst.setDouble(2, s.getPoint());
            pst.setString(3, s.getId());
            if (pst.executeUpdate() > 0) {
                System.out.println("update success");
            } else {
                System.out.println("update error \n");
            }
        } catch (SQLException e) {
            System.out.println("update error \n" + e.toString());
        }
    }

    public static void main(String[] args) {
        MyConnect myConnect = new MyConnect();
        myConnect.connect();
        // myConnect.showData(myConnect.getDataId("DTC1"));
        // myConnect.deleteId("DTC5");
        myConnect.updateId("DTC2", new Student("DTC2", "Vu Cong Tinh", 9.0));
        myConnect.showData(myConnect.getData());
    }
}