ms access - CDate type mismatch error

Question

I'm trying to convert a text field into a date using CDate() in a recordset but keep getting a type mismatch error. The input text format is MMDDYYYY. Does CDate not recognize this format? Do I need a separate function? Any ideas?

Text Date  -> Converted Date
---------     --------------
04122012   -> 04/12/2012


Dim db As DAO.Database
Dim rst As DAO.Recordset

Set db = CurrentDb
Set rst = db.OpenRecordset("tbl_dates", Type:=dbOpenDynaset)

Do Until rst.EOF
rst.Edit
rst![Converted Date]=CDate(rst![Text Date])
rst.Update
rst.MoveNext

Loop

Set rst = Nothing
Set db = Nothing

Answer 1

CDate() won't accept your date string without some type of delimiter between the month, day, and year parts. This attempt fails with a type mismatch error.

? CDate("04122012")

If it's helpful, you can use the IsDate() function to check whether your date strings are in a format CDate() will accept.

? IsDate("04122012")
False
? IsDate("04-12-2012")
True
? IsDate("04/12/2012")
True
? CDate("04-12-2012")
4/12/2012
bar = "04122012" : Debug.Print CDate(Left(bar,2) & "-" & _
    Mid(bar,3,2) & "-" & Right(bar,4))
4/12/2012 

Edit: If there is a mismatch between your system's locale setting and the format of your date strings, you can transform those date strings to yyyy-mm-dd format to avoid problems with CDate().

bar = "04122012" : Debug.Print CDate(Right(bar,4) & "-" & _
    Left(bar,2) & "-" & Mid(bar,3,2))
4/12/2012