Question

Dim _tableBackLogs As System.Data.DataTable 

Do While i - 2 > 0 
_tableBackLogs = Global.DataAccess.GetDataTable("SELECT SubjectID,SubjectName,Grade FROM SubjectPI WHERE RegNo='" & CInt(HttpContext.Current.Session("userName")) & "' AND Status='Fail' AND Semester='" & i - 2 & "'") 
i = i - 2 
Loop 

這樣做會替換DataTable中的以前的數據。我想保留以前的數據，即我希望將新行添加到DataTable，而不用替換以前的行。

Answer 1

與以下替換您的代碼。

Dim _tableBackLogs As New System.Data.DataTable 

Do While i - 2 > 0 
    _tableBackLogs.Merge(Global.DataAccess.GetDataTable("SELECT SubjectID,SubjectName,Grade FROM SubjectPI WHERE RegNo='" & CInt(HttpContext.Current.Session("userName")) & "' AND Status='Fail' AND Semester='" & i - 2 & "'")) 
    i = i - 2 
Loop 

Answer 2

使用合併方法

Dim _tableBackLogs As System.Data.DataTable 

Do While i - 2 > 0 
_tableBackLogs.Merge(Global.DataAccess.GetDataTable("SELECT SubjectID,SubjectName,Grade FROM SubjectPI WHERE RegNo='" & CInt(HttpContext.Current.Session("userName")) & "' AND Status='Fail' AND Semester='" & i - 2 & "'")) 
i = i - 2 
Loop