SQL 服务器的图表构建问题

Chart Building Issue With SQL Server

我正在尝试根据 SQL 服务器中 table 的数据构建饼图,这是我的代码,ASP.NET 和 c#:

ASP.NET

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">

function drawChart() {
        var options = {
            title: 'My Bills'
        };
        $.ajax({
            type: "POST",
            url: "MyPage.aspx/GetChartData",
            data: '{}',
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (r) {
                var data = google.visualization.arrayToDataTable(r.d);
                var chart = new google.visualization.PieChart($("#chart")[0]);
                chart.draw(data, options);
            },
            failure: function (r) {
                alert("Failure");
            },
            error: function (r) {
                alert("Error");
            }
        });
    }

C#

 [WebMethod]
    public static List<object> GetChartData()
    {
        string Chartquery = "SELECT a.[amount] AS 'Amount', DATENAME(Month,a.[myDate]) +' '+ convert(varchar(4),Year(a.[myDate])) As 'Month Year' "
            + "FROM [myTable] a "
            + "left join [mySecondTable] b on a.[ID] = b.[ID] "
            + "left join [myThirdTable] c on c.[code] = b.[code] "

            + "WHERE c.[myName] = John Doe";

        String strConnString = ConfigurationManager.ConnectionStrings["myConnection"].ToString();
        List<object> chartData = new List<object>();

        chartData.Add(new object[]
        {
            "Amount", "Month Year"
        });

        using (SqlConnection con = new SqlConnection(strConnString))
        {
            using (SqlCommand cmd = new SqlCommand(Chartquery))
            {
                cmd.CommandType = CommandType.Text;
                cmd.Connection = con;
                con.Open();

                using (SqlDataReader sdr = cmd.ExecuteReader())
                {
                    while (sdr.Read())
                    {
                        chartData.Add(new object[]
                        {
                            sdr["Amount"].ToString(), sdr["Month Year"].ToString()
                        });
                    }
                }
                con.Close();
                return chartData;
            }
        }
    }

C# 代码 returns 完全正确,我已经对其进行了调试并且效果很好。我的程序编译、构建并运行,但是当它加载页面时,我在页面上收到错误 Pie chart should have a first column of type string。所以我猜它与 ASP 代码有关。

我知道我发布了很多代码,但我想提供我必须提供的所有内容,以便更好地了解我在做什么,并让大家指出任何错误。

关于如何修复上述 Pie chart should have a first column of type string 错误的任何建议?

编辑:

我在 while 循环中添加了 .ToString(),它解决了字符串的问题。现在页面加载没有错误,但图表似乎没有填充数据,即使我的 return chartData 正在返回数据....我页面上唯一显示的是图表标题

有什么建议吗?

你写的地方

chartData.Add(new object[]
{
    sdr["Amount"].ToString(), sdr["Month Year"].ToString()
});

改为

chartData.Add(new object[]
{
    sdr["Month Year"].ToString(), sdr["Amount"]
});

这应该可以解决问题。另外,更改 header 行!