CodeIgniter 3 中基于 MySQL 数据高效生成动态图表教程

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class ChartController extends CI_Controller {

    public function __construct()
    {
        parent::__construct();
        $this->load->database(); // 确保数据库已加载
    }

    /**
     * @brief 获取血液类型图表数据 (低效迭代查询方法)
     */
    public function bloodTypesChartInefficient()
    {
        $chartData = [];

        // 1. 获取所有可用的不重复血液类型
        $blood_types_query = $this->db->query("SELECT BloodType FROM packets WHERE isAvailable = '1' GROUP BY BloodType");
        $blood_types = $blood_types_query->result_array();

        // 2. 遍历每种血液类型，单独查询其数量
        foreach($blood_types as $bt)
        {
            $count_query = $this->db->query("SELECT COUNT(PacketID) as count FROM packets WHERE BloodType = '{$bt['BloodType']}' AND isAvailable = '1'");
            $record = $count_query->result_array();

            if (!empty($record)) {
                $chartData['label'][] = $bt['BloodType'];
                $chartData['data'][] = (int)$record[0]['count']; // 确保数据类型为整数
            }
        }

        // 将数据编码为 JSON 格式
        $data['chart_data'] = json_encode($chartData);

        // 加载视图并传递数据
        $this->load->view('insight', $data);
    }
}