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Mark Stanton wrote:
Keys are intended for the internal workings of the database, they are not meant to be
used like this.

What you want is the WHERE clause, or occasionally the HAVING clause, matching or
excluding rows based on their data.

Keys are NOT data and should not be used as such.

Regards Mark Stanton One small step for mankind...

     I have a table, Reading, that contains three fields: ID, Date, and Meter. Date is the
date the meter is read, and Meter is the meter reading.
I want to know how much electricity (KWH used) I have used each month. The query below will provide that information:

SELECT "Ending"."Date", "Ending"."Meter" -"Beginning"."Meter" AS "KWH Used" FROM "Power". "Reading" AS "Beginning" LEFT JOIN "Power". "Reading" AS" Ending" ON "Ending"."ID" =1 + "Beginning"."ID"

Perhaps you are right about keys being intended for the internal workings of the database. While I don't have an example of one key being the multiple of the other key, it is possible. It just might not have any practical applications.


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