下面一行:难度双
String itemid = reader1.IsDBNull(itemid_Index) ? null : reader1.GetString(itemid_Index);
给我一个运行时错误:
Unable to cast object of type 'System.Double' to type 'System.String'
我试图改变行这样:
Double itemid = reader1.IsDBNull(itemid_Index) ? (Double?)null : reader1.GetDouble(itemid_Index);
,但它给人的以下设计时间错误:
Cannot implicitly convert type 'double?' to 'double'. An explicit conversion exists (are you missing a cast?)
任何想法?
制作'itemid'了''双?否则就像'reader1.GetDouble(itemid_Index)?? null'或者'reader1.GetDouble(itemid_Index).Value'(如果你确定'GetDouble'不会返回null) – crashmstr
'double'对于'index'列似乎是一种奇怪的数据类型... –