一、關於起因
在Excel中我們經常使用Rank函數對數據進行排名操作。而在Access中我們要進行排名是找不到這個Rank函數的，此時我們需要自己書寫VBA代碼或者建立SQL查詢來完成排序操作。
今天我就來講講如何在Access中進行Rank排名操作，首先我給大家分析一下排名的種類跟實現方法。
二、排名的種類跟算法
1、非連續排名
邏輯算法：對於一組數列里的某個數字而言，其非連續排名是指：在該組數列里比該數字大的所有數字的個數+1
2、連續排名
邏輯算法：對於一組數列里的某個數字而言，其連續排名是指：在該組數列里比該數字大的所有非重復數字的個數+1
三、不同的實現方式
首先我們做好准備工作，我們要建立必要表及其內部數據，如下圖所示分別為表的結構及部分初始數據：
1、VBA實現方式
我寫了一個Sub過程RankField，該過程的參數說明如下：
TableRanked：需排名的表名
FieldRanked：數據所在字段的字段名
FieldResult：排名后結果存儲的字段名
NormalRank：是否是常規排名(True是常規排名，非連續排名，Excel中的Rank函數即為非連續排名；False為連續排名)
1 Sub RankField(TableRanked As String, FieldRanked As String, FieldResult As String, NormalRank As Boolean) 2 Dim rs As New ADODB.Recordset 3 Dim rs1 As New ADODB.Recordset 4 rs.Open "Select " & FieldRanked & "," & FieldResult & " From " & TableRanked, CurrentProject.Connection, adOpenDynamic, adLockOptimistic 5 Do Until rs.EOF 6 If NormalRank Then 7 rs1.Open "Select Count(*)+1 as CountNum From " & TableRanked & " Where " & FieldRanked & ">" & rs.Fields(FieldRanked).Value, _ 8 CurrentProject.Connection, adOpenForwardOnly, adLockReadOnly 9 Else 10 rs1.Open "Select Count(*) as CountNum From (Select Distinct " & FieldRanked & " From " & TableRanked & " Where " & FieldRanked & ">=" & rs.Fields(FieldRanked).Value & ")", _ 11 CurrentProject.Connection, adOpenForwardOnly, adLockReadOnly 12 End If 13 rs.Fields(FieldResult).Value = rs1!CountNum.Value 14 rs1.Close 15 rs.MoveNext 16 Loop 17 rs.Close 18 End Sub
按下Ctrl+G,切換到立即窗口,分別輸入如下類似的代碼:
1 RankField "Score","Score","Rank1_VBA",true 2 RankField "Score","Score","Rank2_VBA",False
我們會得到如下類似的結果,Rank1_VBA列為非連續排名結果,Rank2_VBA為連續排名結果:
2、SQL查詢實現方式
相比於VBA代碼方式,在成績值發生修改時,SQL查詢可以自動更新排名數據,而不需要像VBA過程要每次都手動重新運算.
1 SELECT 2 Score.id, 3 Score.Score, 4 Score.Rank1_VBA, 5 Score.Rank2_VBA, 6 (Select Count(*)+1 From score AS Score_1 Where Score_1.Score>Score.Score) AS Rank1, 7 (Select Count(*)+1 From (Select Distinct Score_1.score From score AS Score_1) As tbl Where tbl.Score>Score.Score) AS Rank2 8 FROM Score;
創建這個查詢后,會活的如下所示的運行結果:Rank1與Rank1_VBA對應,Rank2與Rank2_VBA對應.
