简单分页查询实现原理

如何实现分类查询

package jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class QueryCurrentPage {private static String url = "jdbc:mysql://127.0.0.1:3306/study?characterEncoding=UTF-8";private static String userName = "root";private static String passWord = "root";public static void main(String[] args) {queryByPage(2, 4);}/** * 分页查询 * @param currentPage当前页 * @param pageSize每页将显示的数据量 */public static void queryByPage(int currentPage, int pageSize) {try {Class.forName("com.mysql.jdbc.Driver");} catch (ClassNotFoundException e) {e.printStackTrace();}ResultSet resultSet = null;// 将资源声明在try()中,当语句结束,资源将被关闭try (Connection connection = DriverManager.getConnection(url, userName, passWord);PreparedStatement preparedStatement = connection.prepareStatement("select * from employee limit ?,?;");) {preparedStatement.setInt(1, (currentPage - 1) * pageSize);preparedStatement.setInt(2, pageSize);resultSet = preparedStatement.executeQuery();while (resultSet.next()) {System.out.print(resultSet.getInt("id"));System.out.print(resultSet.getString("name"));System.out.print(resultSet.getString("email"));System.out.println(resultSet.getInt("salary"));}} catch (SQLException e) {e.printStackTrace();}}}