爲什麼我的程序thorws此錯誤：無法執行上的System.DateTime和System.Int32

Question

'=' 操作爲什麼我的代碼拋出錯誤 Cannot perform '=' operation on System.DateTime and System.Int32.，

此行拋出錯誤：

DataRow[] dr = ds.Tables[0].Select("HolidayDate=" + SelectedDate); 

但是當我傳遞了像「＃2014-10-12＃」這樣的靜態日期，然後它就起作用了，我還在selectedDate後面加了＃，但程序沒有給出答覆。

完整代碼：

protected void Calndar_SelectionChanged(object sender, EventArgs e) 
{ 

    string SelectedDate = Calndar.SelectedDate.ToString(DateTime.Now.ToString("yyyy") + "-" + "MM-dd"); 
    DataSet ds = (DataSet)Session["Calendar"]; 
    DataRow[] dr = ds.Tables[0].Select("HolidayDate=" + SelectedDate); 
    foreach (DataRow drr in dr) 
    { 
     Response.Write(SelectedDate); 
    } 

字符串SelectedDate門店值，也顯示在的Response.Write

更新後的代碼也沒有。如果你想避免這樣的日子努力

protected void Calndar_SelectionChanged(object sender, EventArgs e) 
{ 
    DateTime SelectedDate =new DateTime(DateTime.Now.Year, Calndar.SelectedDate.Month, Calndar.SelectedDate.Day); 

    DataSet ds = (DataSet)Session["Calendar"]; 
    IEnumerable<DataRow> selectedRows = ds.Tables[0].AsEnumerable().Where(row => (row.Field<DateTime>("HolidayDate") == SelectedDate)); 

    foreach (DataRow drr in selectedRows) 
    { 
     Response.Write(drr[4]); 
    } 
} 

Answer 1

系列化問題，您可以使用Linq to DataSet：

DateTime selectedDate = 
    new DateTime(DateTime.Now.Year, Calndar.SelectedDate.Month, Calndar.SelectedDate.Day); 
DataSet ds = (DataSet)Session["Calendar"]; 

IEnumerable<DataRow> selectedRows = ds.Tables[0].AsEnumerable(). 
    Where(row => (row.Field<DateTime>("HolidayDate") == selectedDate)); 

foreach (DataRow selectedRow in selectedRows) 
...