Your suggestion seems more elegant. However, you missed the mathematical meaning of "BETWEEN" in SQL: it is inclusive of both lower and upper bounds.
In the case raised by Patrice Olivier-Wilson, when an announcement expires on announcements_expiredate, it should not show on that date, and thereafter. But using BETWEEN, it will show on announcements_expiredate, thus a logical error. -----Original Message----- From: Hank [mailto:hes...@gmail.com] Sent: Friday, October 01, 2010 4:10 PM To: Joerg Bruehe Cc: mysql@lists.mysql.com Subject: Re: Not to show until a certain date On Fri, Oct 1, 2010 at 2:34 PM, Joerg Bruehe <joerg.bru...@oracle.com> wrote: > Hi! > > > Hank wrote: >> On Wed, Sep 29, 2010 at 8:33 AM, Patrice Olivier-Wilson >> <b...@biz-comm.com> wrote: >>> On 9/28/10 8:33 PM, Chris W wrote: >>> >>>> SELECT * >>>> FROM announcements >>>> WHERE announcements_expiredate > CURDATE() >>>> AND announcements_postdate <= CURDATE() >>>> ORDER BY announcements_expiredate ASC >> >> Or how about something like this: >> >> SELECT * >> FROM announcements >> WHERE CURDATE() between announcements_postdate and announcements_expiredate >> ORDER BY announcements_expiredate ASC > > The syntax is correct, but I don't think this statement will be > optimized as well as the other proposal: > BETWEEN is intended for "column BETWEEN const1 AND const2", > whereas your statement is "const BETWEEN column1 AND column2". > But that only really matters if there are indexes on the column1 and column2 fields. And for the optimizer, wouldn't it make sense to map BETWEEN into two comparison statements "(column>const1 and column<=const2)" or "(const>column1 and const<=column2)" where both scenarios the optimizer may be able to use indexes on the fields? It's exactly the same as the other proposal: "CURDATE() > announcements_postdate and CURDATE()<= announcements_expiredate" which still is using two different fields for the comparisons... so wouldn't both scenarios end up in the exact same place? -Hank -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=li...@cs.albany.edu -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
