I am trying to create an update query for a financial quarterly forecasting database that will be able to ignore certain fields if outside a given parameter.  Example:

Table 1 contains the following fields: Cost Centers, amount, from period, to period

Table 2 contains the following fields: Cost Centers, employee number, amount, Period 1, Period 2, Period 3 (etc. out to Period 12)

Update Query lists all 12 periods from Table 2 to be updated to the amount in Table 1, but ONLY for the periods within the "from period" and "to period".

As the year progresses we want to be able to leave the historical periods as they are, update for the future periods, but yet not have to re-write the update query each time we revise the forecast.

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Answer from Richard Rost:

Create a parameter query that asks for the BeginDate and EndDate. Then, use the output from this query to feed your update query.

You can specify criteria for running your queries, such as limiting between two dates, checking for specific names, etc. by specifying PARAMETERS in your queries.

This free tutorial on my web site explains how to use parameters in queries:

http://599cd.com/tips/access/parameter-queries/?key=BlFAlEx