PHP和Vue.js进阶指南：如何处理解析和过滤数据的统计图表

<?php
  // 连接数据库
  $conn = mysqli_connect("localhost", "username", "password", "database_name");

  // 执行查询语句
  $result = mysqli_query($conn, "SELECT * FROM table_name");

  // 将查询结果解析为JSON格式
  $data = array();
  while ($row = mysqli_fetch_assoc($result)) {
    $data[] = $row;
  }
  $json_data = json_encode($data);

  // 返回JSON数据给前端
  echo $json_data;
?>

<template>
  <div>
    <select v-model="selectedCategory" @change="filterData">
      <option value="">All</option>
      <option v-for="category in categories" :value="category">{{ category }}</option>
    </select>
    <canvas ref="chart"></canvas>
  </div>
</template>

<script>
import Chart from 'chart.js';

export default {
  data() {
    return {
      rawData: [],
      filteredData: [],
      selectedCategory: '',
      categories: []
    };
  },
  mounted() {
    this.getData();
  },
  methods: {
    getData() {
      // 发送GET请求，获取后端数据
      axios.get('api.php')
        .then(response => {
          this.rawData = response.data;
          this.filteredData = this.rawData;
          this.getCategories();
          this.generateChart();
        })
        .catch(error => {
          console.error(error);
        });
    },
    getCategories() {
      // 获取数据中的分类
      this.categories = [...new Set(this.rawData.map(item => item.category))];
    },
    filterData() {
      // 根据选择的分类过滤数据
      if (this.selectedCategory === '') {
        this.filteredData = this.rawData;
      } else {
        this.filteredData = this.rawData.filter(item => item.category === this.selectedCategory);
      }
      this.generateChart();
    },
    generateChart() {
      // 根据过滤后的数据生成统计图表
      const ctx = this.$refs.chart.getContext('2d');
      const chartData = this.filteredData.map(item => item.value);
      const chartLabels = this.filteredData.map(item => item.label);

      new Chart(ctx, {
        type: 'bar',
        data: {
          labels: chartLabels,
          datasets: [{
            label: 'Chart',
            data: chartData
          }]
        }
      });
    }
  }
};
</script>