For this week’s homework, we will continue to practice with the most widely distributed relational DBMS engine available - SQLite. This tutorial will refresh our understanding of DDL and DML (defining a simple relational schema and loading in data), and then give you a chance to design and implement queries. You will submit your solutions for Section 3 using Gradescope. At a minimum, you will submit a homework with your Lab 4 partner; you may join also decide to merge two lab-pairs together for one submission. In other words, your group must be a minimum of 2 (you and your Lab 4 partner) and a maximum of 4 members (you, your Lab 4 partner, and another Lab 4 pair).
Practice SQL queries in using the online tutorial SQLZoo. You can do this on your own or with a partner. Feel free to skim/skip Tutorials 0 and 1 - they cover some simpler concepts so you can come back if you are struggling with subsequent tutorials. Skim tutorial 2 to make sure you are okay with the basics. Complete tutorials 3,4, and 5 including the quizzes to ensure you have a good understanding of writing various SQL queries.
2. Setting up the
The rest of this assignment should be done with your Homework 7 group.
To begin, copy my settings file into your home directory to
automatically change default
sqlite3 settings. You may have already done this
in Week 4 SQLite tutorial; if your queries are not printing a header and in
lined up columns, that means your defaults are not set up properly and you
need to repeat this step:
$ cp /home/soni/public/cs44/.sqliterc ~/.
Next, create a weekly lab director fir this week run
sqlite3 on the command
line and the name of the database you are creating:
Start by creating a
week09 directory in
cs44/weeklylabs subdirectory and copying over some files:
cd ~/cs44/weeklylabs mkdir week09 cd week09 pwd /home/you/cs44/weeklylabs/week09
and then run
sqlite3 with the name of your workspace database:
To verify that you properly imported settings, you should see a message
about "Loading resources". You can also use
.show and examine
foreign_keys (which should have a value of 1):
$ sqlite3 universityDB -- Loading resources from /home/asas/.sqliterc sqlite> .show echo: off explain: off headers: on mode: column nullvalue: "" output: stdout separator: "$" stats: off width: sqlite> PRAGMA foreign_keys; foreign_keys ------------ 1
2.1. Creating Tables
Using relational schema below, create 4 tables using the
CREATE TABLE command. Be sure to specify types, primary key constraints
(bold), and foreign key constraints
Student(id:integer, name:varchar, major:varchar, level:varchar, age:integer)
Faculty(id:integer, name:varchar, dept:varchar)
Class(name:varchar, time:varchar, room:varchar, facultyID:integer))
As an example this is the SQL command for Student:
CREATE TABLE Student( id INTEGER PRIMARY KEY, name VARCHAR, major VARCHAR, level VARCHAR, age INTEGER);
These are the foreign key constraints:
studentID refers to Student(id)
className refers to Class(name)
facultyID refers to Faculty(id)
When done, use
.table to see all tables created and
review your full schema.
2.2. Importing data
Most SQL engines have some built-in command to bulk-load entries from
some file on disk (as opposed to performing thousands of
commands). I have provided 4 files, one each for the tables you
just defined. These files are located in my public space:
$ ls ~soni/public/cs44/universityDB/ class_start enrolled_start faculty_start student_start
To import, use the following template:
.import 'filename' Table
.import '/home/soni/public/cs44/universityDB/student_start' Student
Load all four tables in order of dependencies to maintain referential
integrity. Errors in importing mean that your schema was not correct; you
may have forgotten a column or used the wrong order or types. You will need
to use the
DROP TABLE command to redefine your schema.
Verify the following queries are correct in your database:
sqlite> SELECT * FROM Student; id name major level age ---------- ---------- ---------- ---------- ---------- 1111 Mo CS SO 20 1122 Peter English JR 20 1234 Tyler Math FR 18 2222 Jo Math SR 21 2323 Jo Math JR 22 3333 Tanya Math JR 21 4444 Malik CS JR 20 4545 Sarah English SR 21 5555 Chris Math FR 19 6666 Charles English FR 18 6767 Sarah Math FR 18 7777 Josh CS SO 19 7878 Heather Math SR 22 8888 Elmo CS SO 20 9999 Jo Math FR 19 sqlite> SELECT COUNT(*) FROM Student; COUNT(*) ---------- 15 sqlite> SELECT COUNT(*) FROM Enrolled; COUNT(*) ---------- 47 sqlite> SELECT COUNT(*) FROM Faculty; COUNT(*) ---------- 6 sqlite> SELECT COUNT(*) FROM Class; COUNT(*) ---------- 11
At this point, you should be able to exit and reload the database. All
contents are saved in the file you originally invoked when running
universityDB). Note that the file is saved locally so
you must return to this folder to reload the database.
sqlite> .exit $ sqlite3 universityDB SQLite version 3.7.9 2011-11-01 00:52:41 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite> .table Class Enrolled Faculty Student
Conversely, if you want to restart, you will need to delete the file in Unix
rm -f universityDB sqlite3 universityDB
Answer the queries below and submit your solutions through Gradescope HW 7.
The files are small enough that you
can manually check for correctness. SQLite recognizes most of standard
SQL query syntax. You need to remember to terminate an SQLite query with
; . While spacing does not impact query parsing, you may want to use it to
make you queries easier to read.
Here is some documentation about queries in SQLite:
SELECT S.name FROM Student S WHERE S.level != 'FR' AND S.age > (SELECT MIN(S2.age) FROM Student S2 WHERE S2.level = 'FR');
For each query, you will need to submit your query. We have provided the expected result for questions 1 and 2 as well as hints for the others to help you check your work. In Gradescope you will need to submit just the query for questions 1 and 2 and both the SQL query and output for questions 3-7. Recall that you can save your Gradescope submission along the way so you do not have to solve all of the queries in one sitting.
Find the names of all CS Majors (Major = 'CS') who are enrolled in the course 'Math06'. (1 result)
name ---------- Mo
Find the name and age of all Junior (Level = 'JR') Math Majors. (2 results)
name age ---------- ---------- Jo 22 Tanya 21
Find the names of all classes that either meet in room R300 or are taught by 'Kelemen' (7 results)
C.name ---------- CS10 ...(remaining results omitted)
Find the names of all CS Majors (Major = 'CS') who are enrolled in the course 'Math21' and are older than some Math freshman (Level='FR') (2 results).
For each Level, print the Level and the average age of students of that Level. (4 results)
Find the names of all students who are not enrolled in any class taught by 'Kelemen'. (4 results)
Find the names of all pairs of students who are enrolled in some class together (54 results).