Good day, Richard. >> RH> <flight_chain ...> >> RH> <flight_options> >> RH> <flight...> >> RH> <flight...> These three flights represent options >> RH> <flight...> >> RH> </flight_options> >> RH> </flight_chain> RH> 1. A journey (flight_chain) between city A and city Z consists of one or RH> more flights. RH> 2. The next flight has to start at the current city, but there may be RH> several flights to choose from. RH> 3. The last flight must end at city Z. RH> Now stage 2 groups the flights to choose among - you can call it RH> something else, but the equivalent of flight_options is there.
Tag "city" executed the same role in my version, that tag "flight_chain" in your version. >> RH> 2. If you nest flights then you'll be forced to repeat data, surely? >> RH> Multiple routes could end up mentioning flight id=123 several times and >> RH> each time have to repeat all possible options from it. >> >> Yes. >> Remember, this is not manner of storing data in DBMS. >> This is manner to visualize for man. RH> So how do I know it's repeated without grabbing a pencil and paper and RH> scrolling back and fore to compare them? Write XML-form, which illustrate, what are you want. I will write request. RH> Are you sure this wouldn't just be easier if you wrote a specialised RH> data-visualiser application? Avarage used can not use library of intermediate language to join DBMS and browser. P.S. Programmers are small percent of all users. >> RH> If I'm going to learn only one query language, it'll be SQL >> RH> because everything uses it. >> >> 'tablename >>;' is better, than to learn php, perl, its library RH> But you're not doing the same thing. I'm not doing? I have write example! >> Term "scheme" means "database scheme" to me :) RH> But you were talking about XML at the time. XML is not stored thing, it is a transport form for scheme. Let's ask concrete questions, ok? >> RH> I'm sat here at my laptop, and I want to get a >> RH> list of flights into a spreadsheet I'm doing for my boss. >> >> Your boss will itself solve "task of travelling-salesman" ? >> By eyes ? RH> No, but my boss wants a list of flights from London to Madrid for next RH> Friday, with prices, times etc. Direct flight? #city[name="London"].flight/c1:c2[#c1 #c2 #day="friday"].#city[name="Madrid"] >>; Roundabout flight? #city[name="London"].(flight/c1:c2[#day="friday" t1-^^.t2>30min].city)*||name="Madrid" ; Prices and times is attributes of FLIGHT. These are in Example 2. http://sql4.by.ru/site/sql40/en/author/wave_eng.htm RH> So what does it matter to me as a user User only use. Difference between realizations of site is important only for authors of site. RH> whether the site is written in TML+Java What will Java do ? RH> And if I'm building the site in PHP anyway (and I'm going to need RH> forms/buttons/etc in some language) then what am I gaining from the TML? >> create view x as >> select city.name as start, city.name as end, flight.t1, flight.t2, day >> from city, flight; >> x >>; RH> Hang on - you're using SQL. Why not just use pgadmin and paste the RH> results from my query if I'm using SQL anyway? paste by hands? RH> Sorry - you didn't eliminate any code there. I simplify code. Compare call of php library for database, getting record set, embrace records in circle by html-tags, call php library for http-communication. RH> But the transport of the data is trivial, assuming I have a webserver RH> and PHP/Perl/ASP/etc. available. 1. Speak not about you, but about average user. You don't know real statistics. 2. Even you make superfluous job. Dmitry Turin http://html6.by.ru http://sql4.by.ru http://computer2.by.ru ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
