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John

Software: Databases

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Is anyone interested in database design. I've been learning about databases for a few months and I think its like objectivism (identitys and relationships). I really like it but I'm alway arguing with people about things like difference between multi-valued attributes and composite attributes. For examply a date attribute is a single valued composite attribute. It represents one date but is a composite of day, month and year. The same is true for an address.

So if your interested in database design I would like to discus it with you.

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I just took a test in my database design class. I certainly know what you're talking about, but right now I don't feel like thinking about normalization forms and many-many relations :-)

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When my class started learning about normalizing table our teacher told us the definitions of partial and transitive dependency. It took me a while to understand it but now that I do I'm starting to like it. Our class only goes up to third normal form but my teacher said there are five. Do you know anything about the other two?

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I just had a test on them. Let's see if I still remember:

1NF: Atomic

2NF: No partial dependencies

3NF: No transitive dependencies

BCNF: All candidate attributes are key

4: No multiline correlations

5NF: No lossy joins

DKNF: Everythign else

* opens book*

BNCF = Boyce-Codd Normal Form: Every determinant is a candidate key.

4NF: No multi-valued dependencies occuring in logicaly unrelated atttributes. No unrelates attributes exit.

5NF: All join dependencies are preserved.

DKNG: Domain Key Normal Form: Every contraint of the relation is a logical consequences of the defintion of the keys and domains

close, but no cigar :-/

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I understand BCNF it just makes sure all alternate keys are identified right? 4NF I think I would need an example to understand. 5NF I think just makes sure all foriegn keys are made in the tables that should have them. DKNF makes sure all the constraints are defined ex. if there is a gender attribute it can only have the value of male or female. I think I can figure it out. My class is an online course from Carnegie Technology Education. It's not really a database design class so they probably just wanted to go over the basics of it. The next unit is on transactions and indexes and the one after that is on current trends in databases. The whole idea of this course is to create an online bookstore using PostgreSQL and JSP. This is the strangest combination I've ever worked with. We use cygwin to run PostgreSQL on our windows systems and we use Apache Tomcat for windows to run JSP. I'm glad I have lots of memory.

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I've used relational DBs for a while now, and got a bit sick of it. I now use an object-relational mapping framework (Hibernate, for Java) to just code objects and have it persist/locate/delete them for me. No more SQL for me! Just object models!

If you're so excited about RDBMS, I think you'll like O/R mapping, or even full OODBs.

public class AynRand extends Aristotle implements IIntellectualHonesty, IRomantism, ICapitalism

{

...

}

:D

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Wow, John, that really is a weird combination....

I did two years of coding in ASP/SQL Server at my old job (I quit shortly after they switched to JSP & Vignette), and lots of PHP/MySQL coding at the blog hosting venture I run. Right now I'm learning VB.Net and creating a mod of the IBuySpy store.

In my opinion, while ASP is a dinosaur and JSP is waaay to complex and slow, PHP/MySQL is a simple, cheap, fast and scalable options for many projects.

However the power of .Net simply blows away everything out there, and its Web Controls are light years ahead of what anyone else has to offer.

Private Function Objectivism(ByVal Reason, ByVal Rights, ByVal Reality) As New Philosophy

End Function

B)

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I know it's a strange combination but if it was run on a linux machine it would make sense (postgresql, apache/tomcat). I'm going get this all set up on a linux machine just as soon as I get my ethernet card (why is it so hard to get an ethernet card to work with linux?).

I don't know if I told you but what's even stranger about it is that I run tomcat and the jdk from my 250 zip disk. Not all the computers at school have tomcat but they do have zip drives so I just keep it on my zip along with all my work files. It also saves time from copying the files back and forth.

I haven't learned anything about the other languages out their except how to spell them but I don't think jsp is that complex. It has all the HTTP headers in two objects (request, response), out (for printing), session (for keeping info), and an easy way to put code in the html. You can even make objects like ShoppingCart and make their scope session with out having to save cookies or extend the url (it's automatic). The part that I like most is the JDBC. It's a lot like using a database in Visual BASIC except it connects directly to the database without going through ODBC although it also supports ODBC connections. I havn't even mentioned java beans, or tag libraries. The coolest thing, which I havn't done yet, is connecting to a database through a java applet. You could make the administration of an entire website through one java applet and it could be used on any browser that supports applets. It could even use swing and look like any visual basic application and have html previews, file uploading, and query analizering. I think it would be cool to run this applet from a cell phone.

Anyway ASP, PHP, I would like to learn them all but their is so much to learn with JAVA first (as long as sun doesn't go under).

Gabriel: I'm going to look into Hibernate.

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Don't worry. Sun won't "go under". The worst case scenarios is them getting bought by IBM, which is a big Java supporter, anyway.

I don't agree that JSPs are complex. The ability to define taglibs, and the upcoming JSF (Java Server Faces - the WebForms kind of thing), and other features make it worth its effort. Maybe it was Vignette who was complex.

Let's not turn this into a flame war, but PHP is severly underpowered, since it must parse, compile and execute the .php file on every request. It's not even a full language. The jboss.org group had to port php-nuke to JSP/Java, since the PHP implementation couldn't handle all their traffic.

Also, J2EE/JSP web applications can be run in many many application servers.

Oracle, IBM, Sybase, basically everyone except Microsoft, are primarly Java shops.

Anyway, wait another 3-4 months. Sun is working with Zend to create Perl and PHP compilers for the JVM. (writting JSPs in perl or php)

Java/JSP is complex, the same way Objectivism is complex. That's reality. Don't over simplify it :-)

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I thought that Microsofts IIS supported JSP or a plugin of some sort. I was going to try to get it set up with IIS since I bought xp pro.

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You can configure Apache Tomcat (http://jakarta.apache.org/tomcat/) to work as an IIS module. Tomcat can run stand-alone too.

Tomcat is not one of the best servlet engines, but it's free and the "reference implementation", cared for by Sun.

If you want to play with other stuff, like PHP or ASP, then integrating it all in IIS makes sense.

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