iteration (for-loop) ms Access with past value - vba

Question

I tried to translate a code from VBA excel to access. My data is a column of prices and I want to compute the returns.
This is the original VBA code in excel:
DerCol = Cells(T.Row, Columns.Count).End(xlToLeft).Column
Cells(T.Row, DerCol + 1) = "Returns"
For i = T.Row + 2 To T.End(xlDown).Row
Cells(i, DerCol + 1) = Application.WorksheetFunction.Ln(Cells(i, T.Column)) - Application.WorksheetFunction.Ln(Cells(i - 1, T.Column))
Next i
To get an idea of the output that I have in excel, click here.
In Access, I created a new column next to the prices' column and I would like to fill in exactly like in excel:
Sub vardaily()
Dim db As Database, T As Object, DerCol As Integer, y As TableDef
Dim rs As DAO.Recordset, i As Integer, strsql As String
'idea = SELECT prices FROM dailypricing, then creates newtable "VAR", copy and prices, compute historical and parametric VAR '
'create a new table var_daily'
Set db = CurrentDb()
'insert the pricing date and the prices from dbo_daily'
db.Execute "CREATE TABLE VAR_daily" _
& "(PricingDate CHAR, Price Number);"
'where clause to select the same traded product only'
db.Execute " INSERT INTO VAR_daily " _
& "SELECT PricingDate, Price " _
& "FROM dbo_PricingDaily " _
& "WHERE IndexId = 1;"
db.Execute " ALTER TABLE VAR_daily " _
& "ADD COLUMN Returns Number;"
'sql request to store prices'
strsql = "SELECT First(Price) as FirstPrice, Last(Price) as EndPrice FROM VAR_daily;"
'dao.recordset of the store prices'
Set rs = db.OpenRecordset(strsql, dbOpenDynaset)
'loop to change the prices'
For i = 2 To i = rs.RecordCount
rs.Edit
rs!Price(i) = Log(rs!Price(i)) - Log(rs!Price(i - 1))
rs.Update
Next i
db.Execute "INSERT INTO VAR_daily " _
& "(Returns) VALUES " _
& "(" & rs![Price] & ");"
End Sub
I have the following table that you can see here
I can not manage with the loop. I have no item in my collection at the end.
I looked at other example of loops like here but I did not find how to make an iteration with the last result.
Sorry, I really am a beginner in Ms Access and SQL. I started this week so I apologize if my question is very basic.
EDIT: I added the images and I replaced Firsttransaction and Lasttransaction by "FirstPrice" and "EndPrice".
EDIT2: Thanks to my new privilege, I can share a sample for those who are interested.

Answer 1

I have updated your complete code to what it should be. Again, I don't have an Access database handy to test it but it compiles and should work:
Sub vardaily()
Dim db As Database
Dim rs As DAO.Recordset, i As Integer, strsql As String
Dim thisPrice, lastPrice
'idea = SELECT prices FROM dailypricing, then creates newtable "VAR", copy and prices, compute historical and parametric VAR '
'create a new table var_daily'
Set db = CurrentDb()
'insert the pricing date and the prices from dbo_daily'
db.Execute "CREATE TABLE VAR_daily" _
& "(PricingDate CHAR, Price Number);"
'where clause to select the same traded product only'
db.Execute " INSERT INTO VAR_daily " _
& "SELECT PricingDate, Price " _
& "FROM dbo_PricingDaily " _
& "WHERE IndexId = 1 " _
& "ORDER BY PricingDate;"
db.Execute " ALTER TABLE VAR_daily " _
& "ADD COLUMN Returns Number;"
'sql request to retrieve store prices'
strsql = "SELECT * FROM VAR_daily ORDER BY PricingDate;" ' just get all fields
'dao.recordset of the store prices'
Set rs = db.OpenRecordset(strsql, dbOpenDynaset)
'loop to change the prices'
lastPrice = rs.Fields("Price") ' get price from first record and remember
rs.MoveNext ' advance to second record and start loop
While (Not rs.EOF())
thisPrice = rs.Fields("Price")
rs.Edit
rs!Returns = Log(thisPrice) - Log(lastPrice)
rs.Update
lastPrice = thisPrice ' remember previous value
rs.MoveNext ' advance to next record
Wend
End Sub