To all who answered thank you. This answer below is the one that I can use to convince him what he proposes is not necessarily safe.
Now I just need to decide how to convince him it was his idea :-) Best Regards, Boyd E. Hemphill [EMAIL PROTECTED] Triand, Inc. www.triand.com O: (512) 248-2287 M: (713) 252-4688 -----Original Message----- From: Michael Stassen [mailto:[EMAIL PROTECTED] Sent: Monday, May 03, 2004 12:57 PM To: Bob Ramsey Cc: [EMAIL PROTECTED] Subject: Re: urban myth? Bob Ramsey wrote: > Ah, but the ordering is not random. As your example has it, the results > are in the order that the entries were inserted into the table. There > is an explanation for the order of the returned data. <snip> Apparently not random, but not in the order inserted either. Consider: create temporary table foo (num int(10)); insert into foo values (1), (2), (3), (4), (5); select * from foo; delete from foo where num = 3; insert into foo values (6); insert into foo values (3); mysql> select * from foo; +------+ | num | +------+ | 1 | | 2 | | 6 | | 4 | | 5 | | 3 | +------+ 6 rows in set (0.01 sec) (Same example as before with the "delete...where num=6" removed.) Note the 6 is where the 3 was originally, because the slot where the first 3 was inserted/deleted was reused for the 6. This trivial example yields results which are ordered neither by num nor by the order inserted. The lesson is clear: The *only* way to be sure your rows are sorted in a particular way is to explicitly request it with an ORDER BY clause, as several others have pointed out. This is really a fundamental principle: It is the data in the row that matters, not how or where it is stored. Michael -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
