查询函数在Java中，返回单个列中的所有值的列表

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class QueryFunctionExample {
    public static void main(String[] args) {
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            // 1. 连接数据库
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");

            // 2. 构建查询语句
            String query = "SELECT column_name FROM table_name";

            // 3. 执行查询
            statement = connection.createStatement();
            resultSet = statement.executeQuery(query);

            // 4. 处理结果
            List<String> values = new ArrayList<>();
            while (resultSet.next()) {
                String value = resultSet.getString("column_name");
                values.add(value);
            }

            // 输出结果
            for (String value : values) {
                System.out.println(value);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 5. 关闭连接
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}