为什么总是需要过程预备语句才能通过(标签-Java|关键词-表达式)

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

public class Example {
    public static void main(String[] args) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        try {
            // 连接数据库
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");

            // 编写SQL语句，并预准备
            String sql = "SELECT * FROM users WHERE age > ?";
            preparedStatement = connection.prepareStatement(sql);

            // 设置参数
            preparedStatement.setInt(1, 18);

            // 执行查询
            resultSet = preparedStatement.executeQuery();

            // 处理结果
            while (resultSet.next()) {
                System.out.println(resultSet.getString("name"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭数据库连接和语句对象
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}