如何根据新记录的等级更新具有预定义排名的列？

Question

我有一个MS Access 2010应用程序，它回写到（后端）SQL服务器。该表的学生ID，测试分数和排名为列。该应用程序有一个表单，该表单从用户处获得输入。当新学生输入他/她的ID，分数和等级时，根据插入的等级，其余的等级必须更新。

对于例如，如果一个新的学生都有得分79，与排名第5，在5当前学生必须改为6，第六级至第七等，在SQL表

之前：

Student_ID Score Rank 
1   89 1 
16   88 2 
25   84 3 
3   81 4 
7   78 5 
15   75 6 
12   72 7 
17   70 8 
56   65 9 
9   64 10 

后：

Student_ID Score Rank 
1   89 1 
16   88 2 
25   84 3 
3   81 4 
7   78 6 
15   75 7 
12   72 8 
17   70 9 
56   65 10 
9   64 11 
10   75 5 

Answer 1

取出秩领域，并创建即时计算的排名（行号）的查询。为了加快速度，请使用此处显示的集合：

Public Function RowCounter(_ 
    ByVal strKey As String, _ 
    ByVal booReset As Boolean, _ 
    Optional ByVal strGroupKey As String) _ 
    As Long 

' Builds consecutive RowIDs in select, append or create query 
' with the possibility of automatic reset. 
' Optionally a grouping key can be passed to reset the row count 
' for every group key. 
' 
' Usage (typical select query): 
' SELECT RowCounter(CStr([ID]),False) AS RowID, * 
' FROM tblSomeTable 
' WHERE (RowCounter(CStr([ID]),False) <> RowCounter("",True)); 
' 
' Usage (with group key): 
' SELECT RowCounter(CStr([ID]),False,CStr[GroupID])) AS RowID, * 
' FROM tblSomeTable 
' WHERE (RowCounter(CStr([ID]),False) <> RowCounter("",True)); 
' 
' The Where statement resets the counter when the query is run 
' and is needed for browsing a select query. 
' 
' Usage (typical append query, manual reset): 
' 1. Reset counter manually: 
' Call RowCounter(vbNullString, False) 
' 2. Run query: 
' INSERT INTO tblTemp (RowID) 
' SELECT RowCounter(CStr([ID]),False) AS RowID, * 
' FROM tblSomeTable; 
' 
' Usage (typical append query, automatic reset): 
' INSERT INTO tblTemp (RowID) 
' SELECT RowCounter(CStr([ID]),False) AS RowID, * 
' FROM tblSomeTable 
' WHERE (RowCounter("",True)=0); 
' 
' 2002-04-13. Cactus Data ApS. CPH 
' 2002-09-09. Str() sometimes fails. Replaced with CStr(). 
' 2005-10-21. Str(col.Count + 1) reduced to col.Count + 1. 
' 2008-02-27. Optional group parameter added. 
' 2010-08-04. Corrected that group key missed first row in group. 

    Static col  As New Collection 
    Static strGroup As String 

    On Error GoTo Err_RowCounter 

    If booReset = True Then 
    Set col = Nothing 
    ElseIf strGroup <> strGroupKey Then 
    Set col = Nothing 
    strGroup = strGroupKey 
    col.Add 1, strKey 
    Else 
    col.Add col.Count + 1, strKey 
    End If 

    RowCounter = col(strKey) 

Exit_RowCounter: 
    Exit Function 

Err_RowCounter: 
    Select Case Err 
    Case 457 
     ' Key is present. 
     Resume Next 
    Case Else 
     ' Some other error. 
     Resume Exit_RowCounter 
    End Select 

End Function 

研究典型用法的内嵌评论。