CS 561 – SQL Programming Assignment 2

CS 561-A & B Page 1 of 2
Database Management Systems I
Fall 2021
CS 561 – SQL Programming Assignment 2
Due Dates: 12/3/2021 (Fri) for Sec. A & B
Objectives: • You will continue with expressing “complex” OLAP queries in SQL. The reports below are
similar in nature with the reports from the assignment #1; however, there are two main
differences between the two: (1) the new reports will require aggregation “outside” the
groups (in assignment #1, all of the aggregates were computed for the rows within the
groups); (2) some of the aggregates in the new reports will be computed based on other
aggregates of the same reports – they are known as “dependent aggregates”.
Description: • Generate 4 separate reports based on the following queries (one report for query #1, one
for query #2, one for query #3 and another for query #4):
1. For each customer, product, month and state combination, compute (1) the
customer's average sale of this product for the given month and state, (2) the
customer’s average sale for the given month and state, but for all other products (3)
the customer’s average sale for the given product and state, but for all other months
and (4) the average sale of the product and the month but for all other states.
2. For customer, product and state, show the average sales before and after each
quarter (e.g., for Q2, show average sales of Q1 and Q3. For “before” Q1 and “after”
Q4, display <NULL>. The “YEAR” attribute is not considered for this query – for
example, both Q1 of 2017 and Q1 of 2018 are considered Q1 regardless of the year.
3. For each product, find the median sales quantity (assume an odd number of sales for
simplicity of presentation). (NOTE – “median” is defined as “denoting or relating to a
value or quantity lying at the midpoint of a frequency distribution of observed values or
quantities, such that there is an equal probability of falling above or below it.” E.g.,
Median value of the list {13, 23, 12, 16, 15, 9, 29} is 15.
For example, given the following sales transactions for Bread, the median quant for Bread
is 3.
PRODUCT QUANT
======= =====
Bread 1
Bread 1
Bread 1
Bread 2
Bread 2
Bread 3
Bread 4
Bread 5
Bread 6
Bread 7
Bread 7
4. For customer and product, find the month by which time, 75% of the sales quantities
have been purchased. Again, for this query, the “YEAR” attribute is not considered.
Another way to view this query is to pretend all 10,000 rows of sales data are from the
same year.
The following are sample report output (NOTE: the numbers shown below are not the actual
aggregate values. You can write simple SQL queries to verify the actual aggregate values).

CS 561-A & B Page 2 of 2
Database Management Systems I
Fall 2021
Report #1:
CUSTOMER PRODUCT MONTH STATE CUST_AVG OTHER_PROD_AVG OTHER_MONTH_AVG OTHER_STATE_AVG
======== ======= ===== ===== ======== ============== =============== ===============
Helen Bread 1 NY 243 1493 199 268
Emily Milk 3 NJ 1426 926 482 478
. . . .
Report #2:
CUSTOMER PRODUCT STATE Q1 BEFORE_AVG AFTER_AVG
======== ======= ===== == ========== =========
Bloom Bread NJ 1 <NULL> 2434
Sam Milk CT 3 254 325
. . . .
Report #3:
PRODUCT MEDIAN QUANT
======= ============
Bread 422
Milk 1976
. . . .
Report #4:
CUSTOMER PRODUCT 75% PURCHASED BY MONTH
======== ======= ======================
Emily Bread 2
Bloom Milk 3
. . . .
Make sure that:
1. Character string data (e.g., customer name and product name) are left justified.
2. Numeric data (e.g., Maximum/minimum Sales Quantities) are right justified.
3. Only standard SQL statements and aggregate function syntaxes are used – if
you’re unsure, please ask the Tas.

Grading: NOTE: A query with syntax errors will lose 50% of the points for the query.
Submission: Submit one file on Canvas containing all of the 4 queries with your name and CWID on it.
The file type must be “TXT”.
Please include a “README” section in the same file if any special instructions are required.
I encourage you to discuss the “ideas” with your TAs as soon as possible (rather than your
classmates, esp, if you have any specific questions), but the final queries must be your own
work. If I determine that your queries are copies of someone else’s, both you and that
someone else will be disciplined (you will receive 0 for the entire assignment) and possibly
receive additional penalties for the course.