小编F.O*_*ary的帖子

我目前正在编写一个跟踪某些股票的小应用程序，我有一个包含股票数据的数据库，并希望将其输出到 WPF 数据网格，但出现以下错误：

无法将“System.Single”类型的对象转换为“System.Double”类型

请原谅我糟糕的编码技巧，因为我已经好几年没有这样做了，我查看了内部异常，但它只是说 null。

    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            using (AppDbContext db = new AppDbContext())
            {
                StockGrid.ItemsSource = db.LowFloatStocks.ToList();
            }
        }
    }
}

股票.cs

#region Day 1 Open Variabes

private int stockId;
private string stockTicker;
private double openingPrice;
private double spike;
private double high;
private double low;
private double closingPrice;

private double gainPercent;
private double gapPercent;
private double highPercent;
private double lowPercent;
private double closePercent;

private string greenToRed;
private string redToGreen;
private …

我有两个表，客户和发票，我必须列出所有客户及其剩余信用。我试图从CreditLimit列中减去发票金额列的总和以给我剩余的积分？

这是我到目前为止的查询

DECLARE @CreditRemaining INT

SELECT 
   @CreditRemaining = (c.CreditLimit - SUM(i.Amount))
FROM 
     Customer c 
INNER JOIN 
     Invoices i on
     c.ID = i.customerId