DLN, Thanks. Interestingly enough, pulling records without a sort was rather random (rather, influence by the last sort) - but once I placed a primary key on the table, the order of unsorted records is always constant, even after a sort (based on numerous tests yesterday and today with the tables and a bunch of selects).
-Richard DL Neil wrote: > Richard, > > > > I guess your "problem" comes from the fact that SQL has no concept > of > > > internal order. If you do not specify an ORDER BY clause, the order > or > > > records returned is undefined, i.e. random. > > > > That's what I was figuring. I asked because I wanted it confirmed. > Thank > > you. > > > > > Of course, MySQL has some kind of internal order depending on many > > > factors, but you may not rely on it. And neither you may rely on the > > > fact that a PRIMARY KEY influences the internal order. You have to > use > > > an ORDER BY clause if you want to get a sorted result (of course, > you > > > want a key to speed up the ORDER BY clause). > > > > Hmmm. Perhaps I'm misled by the default behaviour of other database > engines, > > but I was taught that the primary key was stored in the database to > optimize > > search/insert/delete - which meant *sorted*. That is why you don't > want a > > large (complex) primary key on tables that must run "fast" - the > overhead of > > sorting each insert/delete negatively affects performance. Or so I was > taught, > > anyway (back in the dark ages - primative data structures and all that > <G>). > > As others have said, this is not part of the relational model. > However you are correct - back in the 'good old days' we could rely upon > hierarchical databases to do this, and I'm fairly sure that the early > 'SQL' DBMSes also used to do this because they physically separated the > Primary Key and the 'dependent part' of the row, so that any 'straight' > listing would come out in PK sequence. > > =dn --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
