如何在Kotlin中使用GROUP BY进行限制？

val query = "SELECT customer_id, SUM(amount) as total_amount FROM orders GROUP BY customer_id"

import java.sql.DriverManager
import java.util.Properties

fun main() {
    // 建立与数据库的连接
    val url = "jdbc:mysql://localhost:3306/mydatabase"
    val props = Properties()
    props.setProperty("user", "username")
    props.setProperty("password", "password")
    val conn = DriverManager.getConnection(url, props)

    // 构造查询语句
    val query = "SELECT customer_id, SUM(amount) as total_amount FROM orders GROUP BY customer_id"

    // 执行查询并处理结果
    val stmt = conn.createStatement()
    val resultSet = stmt.executeQuery(query)

    // 处理结果集
    val customerOrders = HashMap<Int, Double>()
    while (resultSet.next()) {
        val customerId = resultSet.getInt("customer_id")
        val totalAmount = resultSet.getDouble("total_amount")
        customerOrders[customerId] = totalAmount
    }

    // 打印结果
    customerOrders.forEach { (customerId, totalAmount) ->
        println("Customer $customerId: Total Amount = $totalAmount")
    }

    // 关闭连接和资源
    resultSet.close()
    stmt.close()
    conn.close()
}