as a totally off-topc question, wouldn't something along the lines of LIMIT COUNT(*)/2, 1 do that trick?
On 4/15/10, Rhino <rhi...@sympatico.ca> wrote: > > > Shawn Green wrote: >> Tompkins Neil wrote: >>> Hi, >>> >>> I've used mainly of the older versions of MySQL. However am looking >>> to port >>> a application across to MySQL 5. My question is when would one >>> decide to >>> use a Stored Procedure over a query written at the application level ? >>> >> >> The decision to encapsulate a particular process or query within a >> stored procedure is usually based on your business needs. >> >> * Common queries that only change by parameters are good candidates >> >> * Complex multi-step queries are good candidates >> >> * If you need an unprivileged user to make a change to a sensitive >> table, you can avoid some security problems by wrapping that process >> in a stored procedure. For example, maybe part of your internal HR >> processes is an application that allows people to update their phone >> numbers but can't be allowed to see the private information in an >> employee's database record. You could create a privileged routine >> called change_phone_number() that could do that without giving the >> application (or another user) the rights to manipulate that table >> directly. >> >> Does this help? >> > The other situation that strongly justifies a stored procedure in place > of an application level query is one that involves a lot of churning > through the database to return only a small amount of data. > > For example, suppose you had to determine the median grade for a test. > Let's say there were a million separate people taking this test (perhaps > something like college admission tests). To find the median, it's > probably best to sort the rows in ascending order by final grade, then > count down from the top until you are halfway through the list. Then you > can find and return the median grade. That involves a lot of I/O: a > million rows to read, then the sorting, then reading down a half million > rows to find the midpoint. But all you're returning is the median. If a > client program has to do that work, all of those I/Os are going to be > sent over the network and cost a lot. But if you write a stored > procedure, it will do all the heavy lifting LOCALLY on the database > server, which will reduce costs dramatically. Only the median gets sent > across the network back to the client program. Obviously, this will save > on both I/O costs and network utilization. > > -- > Rhino > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/mysql?unsub=vegiv...@tuxera.be > > -- Bier met grenadyn Is als mosterd by den wyn Sy die't drinkt, is eene kwezel Hy die't drinkt, is ras een ezel -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
