php+ajax+highchart+json绘图

<div id="departchart" style="min-width:400px;height:400px"></div>

 $.ajax({
            type: "get", //请求方式
            url: "getjsondata.php", //请求地址
            dataType: "Json", //传输的参数，json格式的数据
            success: function(data) { //服务器返回的数据
                $.each(data, function(key, val) {
                    chartdata.push(val);
                })//将数据转为[[],[],[]]格式
                $('#departchart').highcharts({//调用highchart
                    chart: {
                        type: 'column'      
                    },
                    title: {
                        text: '各学院教职工总数'
                    },
                    subtitle: {
                        text: '数据截止 2017-11'
                    },
                    xAxis: {
                        type: 'category',
                        labels: {
                            rotation: -45,
                            style: {
                                fontSize: '13px',
                                fontFamily: 'Verdana, sans-serif'
                            }
                        }
                    },
                    yAxis: {
                        min: 0,
                        title: {
                            text: '人数 (位)'
                        }
                    },
                    legend: {
                        enabled: false
                    },
                    tooltip: {
                        pointFormat: '总人数: <b>{point.y:.1f} 位</b>'
                    },
                    series: [{
                        name: '总人数',
                        data: chartdata,
                        dataLabels: {
                            enabled: true,
                            rotation: -90,
                            color: '#FFFFFF',
                            align: 'right',
                            format: '{point.y:.1f}', // one decimal
                            y: 10, // 10 pixels down from the top
                            style: {
                                fontSize: '13px',
                                fontFamily: 'Verdana, sans-serif'
                            }
                        }
                    }]
                }); //endchart
            } //endsuccess
        }); //endajax

 <?php
        header("Content-type: text/json");
        $servername = "localhost";
        $username   = "";
        $password   = "";
        $dbname     = "";
        // 创建连接
        $con = mysqli_connect($servername, $username, $password, $dbname);
        // 检测连接
        $sql    = " select distinct department ,count(department) from workinfo group by department ";
        $result = mysqli_query($con, $sql);
        if (!$result) {
            printf("Error: %s\n", mysqli_error($con));
            exit();
        }
        while ($rows = mysqli_fetch_array($result, MYSQL_ASSOC)) {      
            $arr[] = array(
                $rows['department'], intval($rows['count(department)']),
            );
        }
        $data = json_encode($arr, JSON_UNESCAPED_UNICODE);
        echo $data;
        mysqli_close($con);