Re: Student asks about Tuples and Relations (SQL Problem)

In article <36379280.7EBB_at_bloomberg.net>, Art S. Kagel <kagel_at_bloomberg.net> writes
>Alex Snoeren wrote:
>>
>> Hello,
>>
>> For a project on my university I'am investigating the possiblity of the
>> following:
>> "Is it possible to retrieve the date of when a certain tuple(record) was
>> created ?
>> Is this being saved somewhere in the RDBMS ?"
>> How can I get this date using SQL?
>
>No. Only if the table schema includes a timestamp column that is being
>maintained.

Perfect relational databases will only deliver the data which the designer has explicitly made available to users. Real-world databases aren't perfect, and may have alternative routes to the data. Transaction logs may not appear in the schema but might be available to authorised users. There might also be system-tables accessible to systemadministrators.

To a first approximation your answer is correct. I'm not sure what level of course Alex is taking and so I'm not sure whether an answer based only on data available to ordinary users is adequate.

-- 
Bernard Peek
bap_at_shrdlu.com