CS145 Assignment #3
Due Wednesday, October 22, 1997
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.
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 286 of the text gives you the principal options regarding types.
Hand in a printout of the commands you use to create your database
schema (it is a good idea to keep this file for the balance of the
Show the response of sqlplus to a request to describe each of your
For example, to see the schema for relation Foo type
Execute about five INSERT commands to insert tuples into one of
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.
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
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 the small ``toy'' databases
often used in classes. The data you generate and load should be on
the order of:
- At least two relations with thousands of tuples
- At least one relation with 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 ensure 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
- 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.
- 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
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.
Considering the following E/R design and ODL design
for a database managing hosts.
Note: the RAHosts entity set, representing hosts that
the university provides to research assistants (RA's)
to do projects at home,
is not shown in the E/R, because the properties of
any RAHost entity can be
decomposed to other entity sets.
The E/R model is --
The ODL model is --
attribute string name;
relationship Set Hooks
attribute string name;
attribute string OS;
relationship Domains HookedIn
interface UnivHosts: Hosts
attribute int UnivID;
interface ResiHosts: Hosts
attribute string Resident;
interface RAHosts: UnivHosts, ResiHosts
Please create relational database schemas as follows --
- E/R style: Convert the E/R model to relational model.
- ODL style: Convert the ODL model to relational model.
Note: class "Host" has no key. Try to make one instead of
borrowing one from "Domain" as in E/R.
- Using nulls: Write one relation (allowing null) representing
the class and subclasses, and explain how it represents all the
Consider the following E/R schema.
- Explain briefly what the two arrows mean.
- Convert the relationship TAfor to a relation, and give all the
Consider a relation with schema R(A, B, C, D) and functional dependencies
A->B, BC->D, D->A.
- What are all the nontrivial functional dependencies that follow from
the given dependencies?
You need only consider single attributes on the right side.
- What are all the keys of R?
- What are all the superkeys that are not (minimal) keys?
Are the following statements true? If so, prove it. Otherwise, disprove it.
Note: You just need a counterexample to disprove a statement.
- If AB->AC, then B->C.
- If AB->C, then A->B or A->C.
- If A->B and BC->D, then ABC->D.
Exercise 3.7.1(e) [p. 154], parts (i) and (ii) only.
Exercise 3.7.4 [p. 155].