Colin Guthrie wrote:
'Twas brillig, and tedd at 11/12/08 18:46 did gyre and gimble:
As for my "Foreign Keys Question", I think the answer is that it
enforces rules upon the configuration (i.e., deleting, altering, and
such), but does not provide any significant service beyond that.
Well that's a fairly significant service in itself. The whole
"deleting data" case is where FK's have saved me significant amount of
coding.
The ON DELETE CASCADE option is key here... "DELETE FROM students
where student_id=1" will remove all traces of that student from the
db... all the course they've attended, all the instructors who have
taught them etc. keeps things nice and tidy without having to put the
structure in your code all over the place.
Col
Is it just me or does anyone else here not like deleting from a
database, I normally have a status field to indicated if a row has been
deleted.
What about historical data, would you not want to know that studentX was
enrolled at some point in the past, if you just delete that student and
all related data how would you know this?
You could also have a 2nd database with the same table structure and
move old/delete data into there.
Clive
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