The Count function helps you easily create a query that, based on any criteria, sums up the number of Access records you have. Here's how to use it.

Countif does not seem to work in Access I could I suppose separate out the codes in the underlying query but I have a feeling it is something more simple but I can't bring it to mind ...

Use Count to count the number of records in an underlying query. For example, you could use Count to count the number of orders shipped to a particular country or region. Although expr can perform a ...

The easiest way is probably to create an Access VBA public function which takes the date parameters, queries the table and returns the appropriate count; and call this function within the UPDATE ...