Project 3
Do not be afraid to create extra columns to get the effect of compound if statements.
As for the player rankings, my goal is for you to play with the data to understand it better.
Ideas to consider are: (1) create your own formulas to combine the results of statistics in meaningful ways, (2) sort the players by how they rank according to particular statistics, (3) use `if' statements to select players satisfying various criteria (if HR>30 and BA>.300)
Graphics to consider are: (1) How well do your selected players compare
to each other and the maximum and/or average in important categories?
(2) what is the distribution of statistics - eg. how many players hit
x home runs, 
?
Try to be creative, if possible.
In lab, start working on the HTML exercise - available from the course WWW page.
Project 4 (the last) will go out on Wednesday.
Relational Databases
Database managements systems (DBMS) are the software which manages access to a database.
Important commercial DBMS include Oracle, Sybase, dBASE, and Microsoft Access.
Dealing with raw files is difficult and ugly. DBMS differ according to the model of data that they present to the user.
The relational database model stores information in tables, and then operates on the tables to extract the desired information. Most modern databases are relational databases because of its freedom.
Query Languages
Databases can contain enormous amounts of information. To get access to what we want, we need to do a database query.
Searching for keywords is not sufficient; suppose we seek all people who have worked for our company for more than 10 years who are earning less than $30,000/year.
The query language allows one to specify report contents and formats.
Query by example enables one to search a single table easily, by selecting which options per domain are acceptable.
Structured query languages like SQL enable one to use relational operations to search multiple tables in complicated ways.
Relational Operations
Query languages for relational databases make use of three different operations:
Select enables one to identify the tuples in a relation which satisfy a particular property.
Project enables one to copy the specified domains instead of the entire tuple.
Join enables us to combine two relations, based on common fields.
These three operations are very powerful, in the sense that you can express a wide variety of things, and further maps nicely to operations the database system can do.
Sample Queries
For the given relational database, how can we get the desired report?
``What is the address and telephone number of the publisher of Exploring Windows 95?''
``Which books are published by Ventana Press?''
``What is the publisher and address associated with Order number O4?''
``Which books were included in Order number O7?''
``How many copies of Exploring Access 7.0 were ordered?''
Geographic Information Systems
Many kinds of important information cannot be naturally encoded as text or numerical data. The latest database systems are begining to support non-text items.
Geographical information systems (GIS) are databases which integrate data with maps.
Example queries with GIS systems would be ``how many people live within ten miles of a McDonald's restaurant?'', or ``what is the closest firehouse to a given address'' or ``where do the bulk of Stony Brook students come from.''
Some of these queries could be performed in regular databases, by matching zip-codes or city names, but many require a stronger knowledge of geography.
There is already a tremendous amount of geographic available on line. Roadmaps and driving instructions are already available.
Global Positioning System
Systems which help cars navigate are starting to become available. Clearly, having maps and directories on a CD-ROM can make it possible for the car to suggest a route.
For such systems to be most effective, there must be a way for the car to figure out where it is on the map.
The global positioning systems (GPS) is a collection of several satellites, each broadcasting very accurate time signals.
By measuring the time it took for the signal to arrive to you, you get a very accurate distance measurement. Combining the results from three different satellites enables a computer to calculate your current position to within 10 meters or so!
Even greater accuracy is possible in military applications. The last bits of the time signals are encrypted, so only military devices can understand them.
GPS is a technology with amazing possibilities - someday, once your car figures out that it was stolen, it can call the police and tell them where it is!
Societal issues - to what extent should machines know where you are?
Multimedia databases for audio and video are now being built, another form of non-text database. But how can you search a library of video?