Modules & VBA :: Unable To Extract Day Number From Date Field And Write It To Day Field

I am trying to do some simple table operations. I have a field (Date) containing dates, and an empty field called Day.

I want to extract the day number from the Date field, and write it to the Day field.

I didn't get very far until I ran into trouble when setting my recordset. I get the error "Too few parameters, expected 1". Clicking "Debug", will highlight the code line "Set rs = db.OpenRecordset(sqlString, dbOpenDynaset)".

So far, my code looks as follows:

Code:
Private Sub Command16_Click()
Dim db As DAO.Database
Dim rs As DAO.Recordset
Dim sqlString As String
Dim dataDay As Byte
'Open connection to current Access database
Set db = CurrentDb()

[Code]...

I am not very familiar with the various types of recordset settings. I just want to be able to read data from the Date field, and write data to the Day field.