CS145 Assignment #3

Due 2:45 PM Thursday, October 23, 2003

On-Line Submission of PDA

You should submit your PDA assignments from this one onward, using the on-line submit script found in /usr/class/cs145/bin/submit. Detailed directions are in a "README" file in the same directory. If you execute this script, it will interact with you and allow you to submit the contents of one directory, in which you should have placed all the files you want to submit. Please include in your directory a README file telling us everything that is in the directory and what role the files play in answering the various parts of the assignment. The submit script knows your login name and will label the copy of your directory accordingly. If your login name doesn't make it obvious who you are, please put your name in the README file.

As you may know, the submit script is "one-way." You cannot change submitted files, but you may submit the directory again. It will then appear to the course staff in a new directory with your login name and a higher number than your previous submission. To avoid things getting out of hand, there is a limit of five submissions per week. Also, to avoid a situation where people are tempted to submit early in case the system goes down just before 2:45PM Thursday, we will make sure we are aware of any systems problems, and extend the deadline if necessary. That is, we want you to finish up and go to class on Thursday mornings, but we're not going to be overly concerned if you need to wait for system availability before submitting the work done before 2:45PM.

Step 3 of Your PDA (Personal Database Application)

Note1: see Recording Your Session in the on-line Getting Started With Oracle document for a guide to preparing output to hand in with your assignment. It will be useful for this and subsequent PDA parts.

Note2: Oracle is not being backed up. You need to save anything you need long-term in the leland file system.

(a)

Write an SQL database schema for your PDA, using the CREATE TABLE commands described in the handout Getting Started With Oracle. Pick suitable datatypes for each attribute. Page 292-293 of the text gives you the principal options regarding types, but Oracle likes you to use VARCHAR2 for character strings. Hand in a file with the commands you use to create your database schema (it is a good idea to keep this file for the balance of the course). Show the response of sqlplus to a request to describe each of your relation schemas. For example, to see the schema for relation Foo type

     DESCRIBE Foo;

(b)

Execute five INSERT commands to insert tuples into one of your relations. Show the response of sqlplus and the relation that results when you issue a SELECT * command. Again, the information on how to do this step is in Getting Started With Oracle.

(c)

Develop a substantial amount of data for your database and load it into your relations using the SQL load command. See The Oracle Bulk Loader for information on how to bulk-load data. To create the data, write a program in any programming language you like that creates large files of records in a format acceptable to the Oracle bulk loader, then load the data into your PDA relations. If you are using real data for your PDA, your program will need to transform the data into files of records conforming to your PDA schema. The rest of you will write a program to fabricate data: your program will generate either random or nonrandom (e.g., sequential) records conforming to your schema. Note that it is both fine and expected for your data values--strings especially--to be meaningless gibberish. The point of generating large amounts of data is so that you can experiment with a database of realistic size, rather than a "toy" database. The data you generate and load should be on the order of:

At least two relations with a few thousand tuples each.
At least one additional relation with (at least) hundreds of tuples.

If the semantics of your application includes relations that are expected to be relatively small (e.g., schools within a university), it is fine to use some small relations, but please make sure that you have relations of the sizes prescribed above as well. When writing a program to fabricate data, there are two important points to keep in mind:

(1): Although you have not (yet) declared keys in your relations, in many cases you probably know that an attribute or set of attributes in a relation will serve as a key. If so, be sure not to generate duplicate values for these attributes.
(2): Your PDA almost certainly includes relations that are expected to join with each other. For example, you may have a Student relation with attribute courseNo that's expected to join with attribute number in relation Course. In generating data, be sure to generate values that actually do join--otherwise all of your interesting queries will have empty results! One way to guarantee joinability is to generate the values in one relation, then use the generated values in one relation to select joining values for the other relation. For example, you could generate course numbers first (either sequentially or randomly), then use these numbers to fill in the courseNo values in the student relation.

Turn in your program code for generating or transforming data, a small sample of the records generated for each relation (5 or so records per relation), and a script showing the loading of your data into Oracle.