如何使用java根据mysql数据库中的日期差异(来自另一个表的日期和当前日期)来更新表中的特定标志

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DatabaseConnection {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/database_name";
    private static final String DB_USERNAME = "username";
    private static final String DB_PASSWORD = "password";

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(DB_URL, DB_USERNAME, DB_PASSWORD);
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.time.LocalDate;

public class DateDifferenceUpdater {
    public static void updateFlagColumn() {
        String selectQuery = "SELECT DATEDIFF(date_column, ?) AS date_diff FROM another_table";
        String updateQuery = "UPDATE target_table SET flag_column = ? WHERE id = ?";

        try (Connection connection = DatabaseConnection.getConnection();
             PreparedStatement selectStatement = connection.prepareStatement(selectQuery);
             PreparedStatement updateStatement = connection.prepareStatement(updateQuery)) {

            // 设置当前日期
            LocalDate currentDate = LocalDate.now();
            selectStatement.setDate(1, java.sql.Date.valueOf(currentDate));

            ResultSet resultSet = selectStatement.executeQuery();
            while (resultSet.next()) {
                int dateDiff = resultSet.getInt("date_diff");

                // 根据日期差异更新特定标志
                if (dateDiff > 0) {
                    updateStatement.setString(1, "标志1");
                } else if (dateDiff < 0) {
                    updateStatement.setString(1, "标志2");
                } else {
                    updateStatement.setString(1, "标志3");
                }

                // 设置要更新的记录ID
                updateStatement.setInt(2, recordId);

                // 执行更新操作
                updateStatement.executeUpdate();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

public class Main {
    public static void main(String[] args) {
        DateDifferenceUpdater.updateFlagColumn();
    }
}