proper method of using a "price" field

[jamie_b]

hello,

table1_ProductList -> has the following fields:
ID (primary key,auto number)
SERNO(text)
DESCR(text)
PRICE(currency)

table2_Jobcard -> has the following fields:
ID (primary key,auto number)
PROD_DESCR_ISSUED (droplist, get 'prod desc' value from table1)
PROD_QTY_ISSUED (decimal)
DATE_ISSUED (datetime)
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PROBLEM/QUESTION :

Let's say I change the PRICE(in table1) on 1 Jan 2005, then all EXISTING records (before 1/1/2004) will also be updated with the new(changed) PRICE.
This is WRONG, right?

What is the correct procedure to use/update the PRICE value ??
Any advice will be greatly appreciated.

Regards,
Jamie.