ASSIGNMENT 1 – 600.315/415 – Database Systems
Part 1: Database Schema Design (35 points)
Your task is to design a database for a new Baltimore-based variant of Uber, call JHUber.
You should support the functions of trip planning, trip pricing, driver (and passenger)
evaluation, car amenity assessment and such things as cost/profit assessment for drivers.
For the purposes of this database, you should assume that JHUber’s computation model
for routes, times and distances is based on pairwise precomputed information between two
landmarks and/or two waypoints. A landmark is defined as a major location (e.g. Johns
Hopkins Hospital, White Marsh Mall, BWI Airport, etc.) and there are O(500) of these,
while waypoints correspond to roughly every street corner (e.g. Pratt and Charles St.),
and there are O(10,000) of these. Every landmark is exactly on a waypoint, while not
every waypoint corresponds to a landmark. The major distinction is that it’s possible
to precompute standard times/distances/costs between any two landmarks, while we only
have space to store the distances/times between adjacent waypoints in a graph (i.e. the 4
adjacent street corners to the north, south, east and west in most cases).
Between any two landmarks are a series of precomputed routes, corresponding to a
list of sequential waypoint pairs that collectively constitute a continuous path between the
In addition, for simplification, you should assume that expected traffic loads (and corresponding standard times between waypoints or landmarks) are precomputed and saved
for only 3 traffic levels (Low, Medium, High), rather than all different times of a day, and
it should be possible from other means for you to compute the expected traffic level on
a given date and time (e.g. Saturday 9/26/20 at 5:00 PM) into one of these 3 categories
based on the day of the week and whether it’s a rush hour time slot or not. You can assume
that these traffic relative loads (Low, Medium, High) are the same for all of Baltimore at
a given date/time.
From the database, it should be possible to answer the following questions:
(a) What amenities are offered by the JHUber car with license number DXZ211 (e.g.
bottled water, iphone charging)?
(b) What is the average age and average total mileage of all cars in the JHUber fleet.
(c) List the names of people who are both drivers and customers and don’t drive an
(d) List the license number, make, model, production year and owner of the single car in
the JHUber database with the highest mileage on the car?
(e) List the license number, make, model, production year and owner of all individual
cars in the JHUber database with mileages in excess of 50,000 miles.
(f) List the date, time, nearest waypoint, owner and driver of all JHUber cars which have
been in an accident.
(g) List the date, time, nearest waypoint and driver of all drivers who have received a
ticket in the database, along with ticket type, infraction details and penalty.
(h) List the make, model, year and mileage of all cars in the database who are driven by
someone other than their owners, as well as the driver name and owner name for that
(i) For each make+model of vehicle, list the average age, minimum age and maximum
age of drivers of that vehicle.
(j) List the average driver review score for each driver in the database who has driven at
least one trip, along with his/her name, age and gender.
(k) For each make+model of vehicle, list the average driver review score for all trips
involving that vehicle.
(l) List the name, address and gender of the driver with the highest average review score
in the database.
(m) List the total miles driven by each driver in the database on 9/24/20.
(n) List the total time driven by each driver in the database on 9/24/20, total miles
driven on that day, and average speed on that day (mph = total miles / total hours).
(o) Given the distance driven by each driver on 9/24/20 and the average mpg of their
make/model/year of their vehicle and the price of gas on 9/24/20, compute the cost
spent by that driver on gas on 9/24/20.
(p) List the total amount spent on gas on 9/24/20, the total driver income on 9/24/20,
and total gross profit (income-gasexpenses) for each driver on 9/24/20.
(q) Assuming that JHUber takes a 10% share on all income to JHUber plus a fixed $2.00
booking fee per trip, what is JHUber’s corporate income for every day this month.
(r) List the latitude, longitude, zip code and standard name of all landmarks in the
(s) List the latitude, longitude, zip code and standard name of all waypoints in the
(t) List the expected traffic volume on September 26th, 2020 at 5PM in Baltimore (Low,
(u) List the standard expected distance and standard expected time on a trip between
Johns Hopkins Hospital and BWI in LOW traffic volume (which will have been precomputed).
(v) List the standard distance and expected time between Johns Hopkins Hospital and
BWI based on the average of all JHUber actual trip distances/times for that specific
trip currently stored in the database.
(w) For customer Russ Taylor with birthdate 2/28/61, what is the expected time, distance and cost of trip tomorrow between landmarks Johns Hopkins Hospital and
BWI airport tomorrow (based on stored standard values for that trip).
(x) For customer Russ Taylor with birthdate 2/28/61, what was the difference between
the expected time, distance and cost of trip on 9/12/20 between landmarks Johns
Hopkins Hospital and BWI airport tomorrow (based on stored standard values for
that trip), and the time, distance and cost of his actual trip on that date.
(y) For all trips between landmarks on 9/12/20, list those where the actual distance
exceeded the expected standard distance for that trip, as well as the driver for that
(z) List the total distance and total expected time in LOW traffic volume for all trips
starting at landmark Johns Hopkins Hospital.
(aa) List the total distance and total expected time in HIGH traffic volume for all trip
segments to all waypoints directly adjacent to Johns Hopkins Hospital.
(bb) List the total distance and total expected time in HIGH traffic volume for all possible
combined 2 segment trips from the waypoint at Johns Hopkins Hospital, and list the
3 waypoint lat/longs for each of these initial trip segments.
(cc) List all drivers and their car types within 2 miles of Johns Hopkins Hospital.
(dd) List all drivers and their car license numbers that travelled a route that include the
Charles and Pratt Street waypoint on 8/24/2020.
(ee) For all drivers in the database, list their most departure landmarks in the database
(and the number of total departures from that landmark).
(ff) What is the average driver rating of the most ticketed 10% of drivers.
(gg) List the number of requested rides for each driver, the total number of rides actually
driven (after cancellations) and the delta the two.
(hh) List the most requested landmark destination, grouped by day of the week traveled.
(ii) List the top 10% of vehicle types reporting lost hours due to unscheduled maintenance,
including the average number of hours lost per month.
(jj) List the driver with the highest total gross income in the database (passenger fare
minus JHUber share).
(kk) List the total amount spent on gas and maintenance for each car in the database.
(ll) List the most profitable driver in the database (total gross income minus total spent
on gass and maintenance for the cars that they drive).
(mm) List the expected time for all trips between landmarks that leave from Johns Hopkins
Homewood Campus in HIGH traffic volume, including time, distance and destination
(nn) For all trips between any 2 landmarks, find the difference between the costs of the
trip for LOW and HIGH traffic volumes.
(oo) List the drivers who drove more than 50,000 miles (combined total from all cars
driven) but have not received a ticket.
(pp) List the customers who have been driven by the driver(s) with the highest review
score and the driver(s) with the lowest review score.
(qq) List the drivers who drive only during the weekends or after 6PM.
(rr) Find the average driver review score for cars with each type of amenity (for all trips
using that car)
(ss) List the drivers who have visited (either arrived or departed from) every landmark in
(tt) What is the average time (between low, medium and high traffic times) to get from
Johns Hopkins Homewood campus to Johns Hopkins Hospital?
(uu) Of the cars with a production year after 2012, what model of car that makes the most
money during low traffic levels and has a driver who lives in Baltimore City?
(vv) What is the average difference in pricing between low and high traffic levels for a ride
from BWI Airport to Homewood campus in a Chevy Volt (any year/owner)?
(ww) What is the license number and make of the most expensive ride you can take during
high traffic levels from Camden Yards to Eddies Grocery Store?
(xx) Find the average number of miles per trip driven by all drivers working on 9/24/20
and the gas mileage of the car they drive.
(yy) What is the most popular JHUber car by gender of driver?
(zz) What is the longest path between any two landmarks in the database?
(aaa) What is the most often visited landmark in the database?
(bbb) Which customer has travelled the most miles?
(ccc) Which make+model+year of car in the JHUber fleet has the best gas mileage?
(ddd) Find the average difference between actual trip time and expected trip time for all 3
traffic conditions(High, Medium and Low).
You can assume that a driver can drive multiple cars, a person can own multiple cars, an
individual car can be driven by multiple drivers, but a car can only be owned by one person.
1.1 (20 points) Design the database using the entity-relationship database model and draw
it. Your design should minimize repetitions of information, and distinguish between
generic and specific/individual instantiations of concepts as discussed in the design
exercise in class. Be sure to underline the primary keys, and also specify all mapping
constraints and participation constraints using the (lower bound,upper bound) syntax
such as (0,1) or (1,N), as well as obligatory participation via a double line. You
may also represent participation constraints via arrows (e.g. ↔, →, ←, → or ⇒),
redunantly to the more precise numeric bounds above, but this is not necessary.
You should very briefly justify any unusual or potentially controversial design decisions
you make. Do not spend much time on such notes.
This section will be graded on aesthetics and completeness as well as correctness.
1.2 (10 points) Represent this database design using the relational model. You should
use a tabular notation and include at least one row of sample values for each relation.
You should very briefly justify any unusual or potentially controversial decisions you
make in the conversion process. Do not spend much time on such notes.
1.3 (5 points) Write relational algebra expressions for queries c, f, h, y, ss, ccc based on
your relational database design. 601.315 students should answer questions for only 3
queries of their choice.
Part 2: Relational Algebra and Relational Calculus (65 pts.)
Consider the following hypothetical database schema. Suppose all bars in the US have a
unique bar license number (BNO) and each drinker is identified by a unique drivers’ license
number (DLicNo). Given that this is the year 2020, all bars implement contact tracing,
with a record of all bar visits and COVID status for all visitors to a bar. For example, every
time a drinker represented by DLicNo goes to a bar represented by BNO, the information
is recorded in the database. The number of times a drinker visits a particular bar can
be obtained by examining the VISIT relation. Likewise, given that this is 2020, given a
variety of monitoring techniques (e.g. face-recognition-based and phone/gps/social-media
monitoring), the database also stores information about a bar visitors likes, purchases, and
activities. The relation LIKES represents all the beers that a particular drinker likes and
the relation SERVES represents all the beers a particular bar serves.
BAR BNO BarName BCity BState
L22174 Murphy’s Towson MD
L31927 Joe’s Lutherville MD
L59871 BatBar Georgetown DC
DRINKER DLicNo DName DCity Age Phone PoliticalParty
AK117229 Donald Trump New York 75 201-555-6666 Republican
UU761326 Melania Trump Slovenia 51 201-555-9999 Independent
ZM193312 Joe Biden Wilmington 76 215-555-7777 Democratic
MD891129 Mike Pence Indianapolis 68 201-555-4321 Republican
YU134618 Ivanka Trump New York 41 201-555-0001 Libertarian
VISIT DLicNo BNO DateOfVisit
AK117229 L22174 2020-09-12
MD891129 L59871 2020-11-05
AK117229 L59871 2020-10-03
LIKES DLicNo BeerName
AK117229 Bud Lite
AK117229 Rolling Rock
MD891129 Sam Adams
SERVES BNO BeerName
L22174 Bud Lite
L59871 Bud Lite
L59871 Rolling Rock
BEER PURCHASE DLicNo BNO BeerName DateOfPurchase
MD891129 L59871 Coors Lite 2020-11-05
YU134618 L22174 Bud Lite 2020-11-05
COVID DIAGNOSIS DLicNo EstimatedStartDate DateOfDiagnosis EstimatedEndDate
YU134618 2020-05-06 2020-05-08 2020-05-20
AK117229 2020-04-01 2020-04-05 2020-04-15
YU134618 2020-08-06 2020-08-09 2020-08-20
COVID VACCINE DLicNo DateOfVaccine Manufacturer
UU761326 2020-10-15 Oxford
ZM193312 2020-10-03 Sputnik5
YU134618 2020-10-02 Merk
Students in 601.315 should answer queries 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.14,
2.15, 2.16, 2.17, 2.18, 2.19, 2.23 in the relational algebra.
Students in 601.315 should also answer any 4 queries of your choice from 2.1, 2.2, 2.3,
2.4, 2.9, and 2.10 in the relational calculus.
Students in 601.415 and 601.615 should answer all 23 of the queries below in the relational algebra.
Students in 601.415 and 601.615 should also answer queries 2.1, 2.2, 2.3, 2.4, 2.9, and
2.10 in the relational calculus.
2.1 List the name and political party for all individuals who have visited a bar on the
same day that Ivanka Trump has visited that bar.
2.2 List the names of bars in Maryland that are not in Baltimore and do not serve Bud
2.3 List the names of all people under 30 who have visited at least one bar in Georgetown
and like Bud Lite and do not like Miller Lite.
2.4 List the name and age of everyone who has visited at least one bar that Donald Trump
2.5 List the names and ages of all people who have visited every bar in Towson.
2.6 List the name and birthdate for all individuals who have neither visited a bar nor
suffered from COVID.
2.7 List the names and ages of people who have visited every bar that Donald Trump has
visited and have never visited a bar that Joe Biden has visited.
2.8 List the names of people who have never drunk a beer named for them (e.g. “Sam
Adams” drinking a beer called “Sam Adams”), but have visited at least 1 bar named
2.9 List the name of every bar that serves a beer that Donald Trump doesn’t like.
2.10 List the name of every bar in Towson that serves no beer that is served in a Bar in
2.11 List the name of all beers that both Donald Trump and Ivanka Trump like and are
served at the same bar in the database (i.e. a bar where both people could order a
beer that they like).
2.12 List the name, city and state of the bar that serves the greatest number of different
2.13 List the name and age of the drinker that likes the fewest number of different beers
but likes at least one beer.
2.14 List the name and Political Party of all drinkers who like no beer that Donald Trump
or Mike Pence likes.
2.15 List the name and Political Party of all drinkers who like every beer that Donald
2.16 List the names of all beers purchased by people while they were suffering from COVID.
2.17 List the name of every bar that Donald Trump has visited more than once.
2.18 List the name and phone number of each person who visited a bar on the same date
that Ivanka Trump visited the bar during the date window when she likely had covid.
2.19 List the name and phone number of each person who visited a bar on the same date
as any COVID-19 sufferer who visited the bar during the date window when they
likely had covid.
2.20 For all people who have visited a bar during the time window they have been suffering
from COVID-19, list a 4-tuple of the name of that individual, the name of the bar
that they visited, the estimated start date of their COVID and estimated end date of
their COVID. If an individual has visited 3 bars while suffering from COVID, then
you should list 3 separate tuples for that person (one for each bar).
2.21 List the names and ages of people who have visited at least every bar that Joe Biden
has visited, and has visited all of these bars the identical number of times that Joe
Biden has visited the bar.
2.22 List the name and age and political party of all drinkers who were vaccinated for
COVID and then subsequently tested positive for COVID on a different date.
2.23 List the name and age of drinkers who have purchased all of the beers that are served
by BatBar and also purchased them at BatBar