c# - 从数据库中获取实时图表数据

Question

我有一个名为 tblWeeklyAudit 的表，其中包含多行数据。我想阅读它并在实时图表上显示它。代码如下所示。

using LiveCharts;
using LiveCharts.Wpf;
using System;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Windows;
using static MAS.clsPUB;

namespace MAS.Windows
{
    /// <summary>
    /// Interaction logic for Dash.xaml
    /// </summary>
    public partial class Dash : Window
    {
        public SeriesCollection SeriesCollection { get; set; }
        public string[] Labels { get; set; }
        //public Func<double, string> YFormatter { get; set; }


        public Dash()
        {
            InitializeComponent();
            LoadData();
        }

        private void LoadData()
        {
            double test =0;
            if (CON.State == ConnectionState.Open)
            {
                CON.Close();
            }

            CON.ConnectionString = ConfigurationManager.ConnectionStrings["conDB"].ConnectionString;
            CON.Open();
            CMD = new SqlCommand("select * from tblWeeklyAudit", CON);
            RDR = CMD.ExecuteReader();
            if (RDR.Read())
            {
                 test = Convert.ToDouble(RDR["Defects"]);
            }


            SeriesCollection = new SeriesCollection
            {
                new LineSeries
                {
                    Values = new ChartValues<double> { test }
                },  

            };

            Labels = new[] { "Jan", "Feb", "Mar", "Apr", "May" };


            DataContext = this;
        }
    }
}

图表值由这一行给出，我已经从该缺陷表中调用了表 tblWeeklyAudit。它有几个浮点值行

Values = new ChartValues<double> { test }

Answer 1

将双精度值添加到 aList<double>然后传递给ChartValues<double>类的构造函数：

private void LoadData()
{
    List<double> allValues = new List<double>();
    if (CON.State == ConnectionState.Open)
    {
        CON.Close();
    }

    CON.ConnectionString = ConfigurationManager.ConnectionStrings["conDB"].ConnectionString;
    CON.Open();
    CMD = new SqlCommand("select * from tblWeeklyAudit", CON);
    RDR = CMD.ExecuteReader();
    while (RDR.Read())
    {
        allValues.Add(Convert.ToDouble(RDR["Defects"]));
    }

    SeriesCollection = new SeriesCollection
            {
                new LineSeries
                {
                    Values = new ChartValues<double>(allValues)
                }
            };

    Labels = new[] { "Jan", "Feb", "Mar", "Apr", "May" };


    DataContext = this;
}

Answer 2

要阅读多行，请执行以下操作：

var List<double> allValues = new List<double>();

if (RDR.HasRows)
        {
            while (RDR.Read())
            {
               allValues.Add(Convert.ToDouble(RDR["Defects"]));
            }
        }

然后在您的 SeriesCollection 中使用 allValues。