Totalling Expressions Follow Up - Allen Browne?

[Sue Compelling]

Hi Allen

Hmmm - my next field is a calculated attrition rate using the following
expression (which worked successfully from your previous post) - however I
have an error message about the aggregate functions in this expression. PS -
Difference is derived from an expression I used in the QUERY (as is
PlannedYear for that matter - as the date in the table is mmm-yyyy).

Any options?

=Sum(IIf([PlannedYear]=2005,([Difference])/Sum([Started]),Null))

 

[Allen Browne]

The article in the previous post explained how to typecast the calculated
field so JET would understand the data type correctly. That's the usual
reason why expressions fail. Here is is again:
http://allenbrowne.com/ser-45.html

The formatting of the date is not the issue. If it is a real date/time
field, it will be stored internally as a fractional number, and just
formatted for display purposes.

If you divisor is zero, it will error.