DataReader ASP.NET (Visual Basic) 的问题
我有这个问题：
[InvalidOperationException: No data exists for the row / column.]
System.Data.OleDb.OleDbDataReader.DoValueCheck(Int32 ordinal) +1029063
System.Data.OleDb.OleDbDataReader.GetInt32(Int32 ordinal) +12
ASP.addsousvoyage_aspx.hdVoyage_SelectedIndexChanged(Object sender, EventArgs e) in C:\Users\ZiGi\Desktop\VisualDesign\addSousVoyage.aspx:222
System.Web.UI.WebControls.ListControl.OnSelectedIndexChanged(EventArgs e) +111
System.Web.UI.WebControls.DropDownList.RaisePostDataChangedEvent() +134
System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.RaisePostDataChangedEvent() +10
System.Web.UI.Page.RaiseChangedEvents() +165
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1485
当我这样做时：
MsgBox(myReader1.GetInt32(0).ToString)
即使：
MsgBox(myReader1.FieldCount) 返回 1 作为值，并且 field(0) 是整数。
有什么问题吗？
I have this problem :
[InvalidOperationException: No data exists for the row / column.]
System.Data.OleDb.OleDbDataReader.DoValueCheck(Int32 ordinal) +1029063
System.Data.OleDb.OleDbDataReader.GetInt32(Int32 ordinal) +12
ASP.addsousvoyage_aspx.hdVoyage_SelectedIndexChanged(Object sender, EventArgs e) in C:\Users\ZiGi\Desktop\VisualDesign\addSousVoyage.aspx:222
System.Web.UI.WebControls.ListControl.OnSelectedIndexChanged(EventArgs e) +111
System.Web.UI.WebControls.DropDownList.RaisePostDataChangedEvent() +134
System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.RaisePostDataChangedEvent() +10
System.Web.UI.Page.RaiseChangedEvents() +165
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1485
When I do this :
MsgBox(myReader1.GetInt32(0).ToString)
Even if :
MsgBox(myReader1.FieldCount) returning 1 as value and the field(0) is integer.
What's the problem ?
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评论（1）
您是否忘记执行 myReader1.Read() ？
我认为当忘记时可能会发生此错误。
Have you forgotten to do a myReader1.Read()?
I think this error can occur when it's forgotten.