Iqra Javed

README.md

@@ -76,30 +76,37 @@ column names in the following tables. We'll use `setup.sql` later.
   * Use foreign keys for this, as well.
 
 * Run the queries in the file `setup.sql`. This will populate the tables.
+    -> run command .read setup.sql to read queries from file
   * Fix any errors at this point by making sure your tables are correct.
   * `DROP TABLE` can be used to delete a table so you can recreate it with
     `CREATE TABLE`.
 
+Good resource for wildcard operators: https://www.w3schools.com/sql/sql_wildcards.asp
 * Write SQL `SELECT` queries that:
   * Show all albums.
-  * Show all albums made between 1975 and 1990.
+
+  * Show all albums made between 1975 and 1990. 
+
   * Show all albums whose names start with `Super D`.
-  * Show all albums that have no release year.
+
+  * Show all albums that have no release year. 
 
 * Write SQL `SELECT` queries that:
   * Show all track titles from `Super Funky Album`.
+
   * Same query as above, but rename the column from `title` to `Track_Title` in
     the output.
 
   * Select all album titles by `Han Solo`.
-
+  
   * Select the average year all albums were released.
 
   * Select the average year all albums by `Leia and the Ewoks` were released.
-
+  
   * Select the number of artists.
 
   * Select the number of tracks on `Super Dubstep Album`.
+
 
 ### Exercises, Day 2
 
@@ -135,3 +142,4 @@ Write queries that:
 Submit a file `notes.sql` with the queries that build (`CREATE TABLE`/`INSERT`)
 and query the database as noted above.
 
+.

musiq.sql

@@ -0,0 +1,49 @@
+--********************************       COMMANDS TO CREATE ALL TABLES FOR MUSIC DB       ************************************
+CREATE TABLE track (id INTEGER PRIMARY KEY AUTOINCREMENT, title VARCHAR(128), album_id INTEGER REFERENCES album(id));
+CREATE TABLE album (id INTEGER PRIMARY KEY AUTOINCREMENT, title VARCHAR(128) NOT NULL, release_year INT);
+CREATE TABLE artist (id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(128) NOT NULL);
+CREATE TABLE artist_album (artist_id INTEGER REFERENCES artist(id), album_id INTEGER REFERENCES album(id));
+PRAGMA foreign_keys=ON;
+.read setup.sql
+.headers on
+.mode column
+--*****************************************************************************************************************************
+
+-- Write SQL `SELECT` queries that:
+  -- Show all albums.
+    SELECT * FROM album; 
+
+  -- Show all albums made between 1975 and 1990. 
+    SELECT * FROM album WHERE release_year BETWEEN 1975 AND 1990; --start & end inclusive
+    SELECT * FROM album WHERE release_year > 1975 AND release_year < 1990 --start & end exclusive
+
+  -- Show all albums whose names start with `Super D`.
+    SELECT * FROM album WHERE title LIKE 'SUPER D%';
+
+  -- Show all albums that have no release year. 
+    SELECT * FROM album WHERE release_year IS NULL;
+
+-- Write SQL `SELECT` queries that:
+  -- Show all track titles from `Super Funky Album`.
+    SELECT track.title FROM track, album WHERE track.album_id=album.id AND album.title='Super Funky Album';
+    --resource: http://www1.udel.edu/evelyn/SQL-Class2/SQLclass2_2tblEg.html
+
+  -- Same query as above, but rename the column from `title` to `Track_Title` in the output.
+    SELECT track.title AS 'Track_Title' FROM track, album WHERE track.album_id=album.id AND album.title='Super Funky Album';
+    --resource: https://www.w3schools.com/sql/sql_alias.asp
+
+  -- Select all album titles by `Han Solo`.  
+    SELECT album.title FROM album, artist, artist_album WHERE album.id=artist_album.album_id AND artist.id=artist_album.artist_id AND artist.name='Han Solo';
+
+  -- Select the average year all albums were released. 
+    SELECT AVG(release_year) FROM album;
+
+  -- Select the average year all albums by `Leia and the Ewoks` were released. 
+    SELECT AVG(release_year) FROM album al, artist ar, artist_album aa WHERE aa.artist_id=ar.id AND aa.album_id=al.id AND ar.name='Leia and the Ewoks'; 
+
+  -- Select the number of artists.
+    SELECT COUNT(id) FROM artist;
+    --resource: https://www.lifewire.com/counting-values-with-sql-count-function-1019771
+
+  -- Select the number of tracks on `Super Dubstep Album`.
+    SELECT COUNT(track.id) FROM track , album  WHERE track.album_id=album.id AND album.title='Super Dubstep Album';

notes.sql

@@ -0,0 +1,54 @@
+--Create a database for taking notes.
+
+-- ******************************************** COMMANDS TO CREATE ALL TABLES FOR NOTES DB ********************************************
+.headers on
+.mode column
+PRAGMA foreign_keys=ON;
+CREATE TABLE author (id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(128) NOT NULL);
+CREATE TABLE note (id INTEGER PRIMARY KEY AUTOINCREMENT, title VARCHAR(255), content TEXT, author_id INTEGER REFERENCES author(id) ON DELETE CASCADE, created_at DATE DEFAULT datetime('now','localtime'), last_modified DATE DEFAULT NULL);
+-- command to test last_modified: UPDATE note SET title = 'Iqra''s Note', last_modified = datetime('now','localtime') WHERE id = 1;
+CREATE TABLE note (id INTEGER PRIMARY KEY AUTOINCREMENT, title VARCHAR(255), content TEXT, author_id INTEGER REFERENCES author(id) ON DELETE CASCADE ON UPDATE CASCADE, created_at DATE DEFAULT (datetime('now','localtime')), last_modified DATE DEFAULT NULL);
+--*************************************************************************************************************************************
+
+
+-- What are the columns that a note table needs?
+    id, title, content, author_id, created_at, last_modfied
+
+-- If you have a timestamp field, how do you auto-populate it with the date?
+    set default 
+
+-- A note should have a foreign key pointing to an author in an author table.
+
+-- What columns are needed for the author table?
+    id, name
+
+-- Write queries that:
+
+-- Insert authors to the author table.
+    see setupNotesDB.sql
+
+-- Insert notes to the note table.
+    see setupNotesDB.sql
+-- Select all notes by an author's name.
+    SELECT note.title FROM note, author  WHERE note.author_id=author.id AND author.name = 'Author1';
+
+-- Select author for a particular note by note ID.
+    SELECT author.name FROM author, note WHERE author.id=note.author_id AND note.id=10;
+
+-- Select the names of all the authors along with the number of notes they each have. (Hint: `GROUP BY`.)
+    SELECT COUNT(note.author_id), author.name FROM note, author WHERE note.author_id=author.id GROUP BY author.name;
+
+-- Delete authors from the author table.
+  -- Note that SQLite doesn't enforce foreign key constrains by default. You have
+  -- to enable them by running `PRAGMA foreign_keys = ON;` before your queries.
+    DELETE FROM author WHERE author.id=3;
+
+  -- What happens when you try to delete an author with an existing note?
+    Error: FOREIGN KEY constraint failed
+  -- How can you prevent this?
+    By adding ON DELETE CASCADE in the foreign key definition.
+    --resource: https://stackoverflow.com/questions/15443913/sqlite3-foreign-key-constraint-failed
+
+
+-- Submit a file `notes.sql` with the queries that build (`CREATE TABLE`/`INSERT`)
+-- and query the database as noted above.

setupNotesDB.sql

@@ -0,0 +1,31 @@
+INSERT INTO author (name) VALUES ('Author1');
+INSERT INTO author (name) VALUES ('Author2');
+INSERT INTO author (name) VALUES ('Author3');
+INSERT INTO author (name) VALUES ('Author4');
+INSERT INTO author (name) VALUES ('Author5');
+
+
+INSERT INTO note (title, content, author_id) VALUES ('Note1', 'First note''s content', 4);
+INSERT INTO note (title, content, author_id) VALUES ('Note2', 'Second note''s content', 1);
+INSERT INTO note (title, content, author_id) VALUES ('Note3', 'Third note''s content', 4);
+INSERT INTO note (title, content, author_id) VALUES ('Note4', 'Fourth note''s content', 3);
+INSERT INTO note (title, content, author_id) VALUES ('Note5', 'Fifth note''s content', 5);
+INSERT INTO note (title, content, author_id) VALUES ('Note6', 'Sixth note''s content', 2);
+INSERT INTO note (title, content, author_id) VALUES ('Note7', 'Seventh note''s content', 2);
+INSERT INTO note (title, content, author_id) VALUES ('Note8', 'Eighth note''s content', 4);
+INSERT INTO note (title, content, author_id) VALUES ('Note9', 'Ninth note''s content', 2);
+INSERT INTO note (title, content, author_id) VALUES ('Note10', 'Tenth note''s content', 5);
+INSERT INTO note (title, content, author_id) VALUES ('Note11', 'Eleventh note''s content', 1);
+INSERT INTO note (title, content, author_id) VALUES ('Note12', 'Twelveth note''s content', 4);
+INSERT INTO note (title, content, author_id) VALUES ('Note13', 'Thirteenth note''s content', 3);
+INSERT INTO note (title, content, author_id) VALUES ('Note14', 'Fourteenth note''s content', 4);
+INSERT INTO note (title, content, author_id) VALUES ('Note15', 'Fifteenth note''s content', 5);
+
+-- HOW MANY NOTES DOES EACH AUTHOR HAVE --
+/*
+Author1: 2
+Author2: 3
+Author3: 2
+Author4: 5
+Author5: 3
+*/