如何取得上一年的累计记录？

Question

在 MS Access 中，我有一个如下表：

FY    Percent   
2015    5%  
2016    5%  
2017    5%  
2018    5%  
2019    5%  
2020    5%  

现在我想添加一个计算行，该行的计算应该如下所示：

FY      Calculated
2015    P * 1 (Multiply the value by 1 for first year)
2016    P * 2015 Calculated value (the above value)
2017    P * 2016 Calculated Value
2018    P * 2017 Calculated Value
2019    P * 2018 Calculated Value
2020    P * 2019 Calculated Value
2021    P * 2020 Calculated Value

如何查询？

Answer 1

在普通的 Access 的 SQL 方言中无法做到这一点。因此，VBA 是不二之选。

您需要创建一个表格来保存这些值。假设您的输出表是这样的：

表：tbl_output

FY            Integer
Calculated    Double

VBA 代码：

public sub fillCalculatedValues()
    Dim db as DAO.Database, rsIn as DAO.RecordSet, rsOut as DAO.RecordSet
    Dim strSQL as String
    Dim value as Double, fy as Integer, i as Integer

    ' Connect to the current database
    Set db = currentDb()

    ' Get the values from your input table (let's say it is called tbl_in) in read only mode
    strSQL = "SELECT * FROM tbl_in ORDER BY FY"
    rsIn = db.OpenRecordSet(strSQL, dbOpenDynaset, dbReadOnly)

    ' Initialize your output table
    strSQL = "DELETE FROM tbl_output"
    DoCmd.RunSQL strSQL

    ' Open the output table (allowing edits)
    rsOut = db.OpenRecordset("tbl_output", dbOpenDynaset, dbEditAdd)

    ' Read the input row by row, and insert a new row in the output
    with rsIn
        .moveFirst
        i = 1
        value = 1
        do
            fy = ![FY]     ' Read the field FY from rsIn
            ' Insert the new row in the output table
            rsOut.addNew
                rsOut![FY] = fy
                rsOut![calculated] = value
            rsOut.update
            ' Update the calculated value
            value = value * ![percent]
            ' Advance one row
            .moveNext
        loop until .EOF  ' Loop until you get to the end of the table
    end with
    ' Close everything
    rsOut.close
    rsIn.close
    db.close
end sub

这只是一个例子。您应该修改它以满足您的特定需求

希望这会有所帮助。

---

PS：

• 给你一个小彩蛋：The Ten Commandments of Access
• 如果您愿意从 Access 升级到更强大的 RDBMS，我建议您尝试使用 MySQL。您可以在 MySQL 中使用一些技巧来执行此类操作。您可以take a look to this post 了解如何对 MySQL 中的一组行进行累积求和，并满足您的需求（毕竟，您正在制作累积产品）

Answer 2

我不确定你的意思，也许

SELECT t.FY, 
     t.Calculated, 
     Nz((SELECT Max(CPercent) 
         FROM tFY 
         WHERE FY< t.FY),1) * Percent AS [Last Value]
FROM tFY AS t

然后，重新评论

SELECT t.FY,
      (SELECT Sum(Percent) FROM tFY WHERE FY<= t.FY) AS [Calc Value]
FROM tFY AS t;

Answer 3

试试这个可能对你有帮助

select fy,Percent as curr_percent, sum(Percent) over (order by fy) as cal_field from tbl_cal_field;