On 10/4/06 12:20 PM, "Aaron Bono" <[EMAIL PROTECTED]> wrote:
> On 10/4/06, Erik Jones <[EMAIL PROTECTED]> wrote: >> >> Aaron Bono wrote: >>> On 10/4/06, *Erik Jones* <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> >>> wrote: >>> >>> There is one non-SQL related reason that I like to be able to order >>> columns, at least the way they are displayed whenever the table is >>> described: human comprehension. For example, I like to group all >>> keys >>> in a table before data, that includes primary as well as foreign >>> keys. >>> So, say I'm building on to an existing application and I need to do >> an >>> ALTER TABLE on an existing table to add a foreign key to an existing >>> table. I'd like that key to be listed with the other keys, but >>> presently that's not possible in a simple way and, to be honest, I >>> usually just go without as the process you've described below is too >>> prone to user (human) error when dealing with live, sensitive data >> for >>> me to want to mess with it. >>> >>> >>> Ah, but it is possible... if you use views. >>> >>> I recommend you build views and query off them. Then you can control >>> the order the columns will appear. >> Which would be great if I didn't have (many) thousands of lines of code >> that already use the tables. Besides, this is no where near a 'make or >> break' thing. It's just a matter of aesthetic preference. Ah, but it *is* a "make or break thing." I have seen more than one application crash because some developer didn't understand that columns in a relation (table) have no defined order. This (along with its sister axiom that rows have no defined order) is one of the most commonly misunderstood aspects of relational databases. > > > > So do it as needed and convert your application slowly. > > I just name my views as table_name_vw so all you have to do is modify your > queries to hit the _vw instead of just the table. That shouldn't take much > time to refactor. > > ================================================================== > Aaron Bono > Aranya Software Technologies, Inc. > http://www.aranya.com > http://codeelixir.com > ================================================================== -- Daryl http://itsallsemantics.com ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
