fixing minor discrepencies

lab-3/music-store-app/sql/queries.sql

@@ -28,6 +28,7 @@ INNER JOIN Artist
 	ON Album.artist_id=Artist.id 
 INNER JOIN Genre
 	ON Album.genre_id=Genre.id 
+GROUP BY title /* group by album title to avoid duplicate rows */
 ORDER BY title ASC;
 
 /* 1c. Retrieve a list of Albums
@@ -37,8 +38,6 @@ Include ALL albums, even those without tracks.
 Order by title (a-z) */
 SELECT Album.title, Album.price, Artist.first_name, Artist.last_name, Genre.name AS genre, (SELECT COUNT(*) FROM Track WHERE Album.upc=Track.album_upc) AS num_tracks
 FROM Album /* notice the nested query, aggregate function and aliases! */
-LEFT JOIN Track /* LEFT JOIN causes all Albums to be returned, even when no matching record in Track table */
-	ON Album.upc=Track.album_upc 
 INNER JOIN Artist 
 	ON Album.artist_id=Artist.id 
 INNER JOIN Genre

lab-5/music-store-app/index.php

@@ -17,7 +17,6 @@ if (mysqli_connect_errno()) {
 
 // define the SQL query to run (from lab 3!)
 $sql = "SELECT Album.title, Album.price, Artist.first_name, Artist.last_name, Genre.name AS genre, (SELECT COUNT(*) FROM Track WHERE Album.upc=Track.album_upc) AS num_tracks FROM Album 
-LEFT JOIN Track ON Album.upc=Track.album_upc 
 INNER JOIN Artist 
 	ON Album.artist_id=Artist.id 
 INNER JOIN Genre

lab-5/music-store-app/sql/queries.sql

@@ -28,6 +28,7 @@ INNER JOIN Artist
 	ON Album.artist_id=Artist.id 
 INNER JOIN Genre
 	ON Album.genre_id=Genre.id 
+GROUP BY title /* group by album title to avoid duplicate rows */
 ORDER BY title ASC;
 
 /* 1c. Retrieve a list of Albums
@@ -37,8 +38,6 @@ Include ALL albums, even those without tracks.
 Order by title (a-z) */
 SELECT Album.title, Album.price, Artist.first_name, Artist.last_name, Genre.name AS genre, (SELECT COUNT(*) FROM Track WHERE Album.upc=Track.album_upc) AS num_tracks
 FROM Album /* notice the nested query, aggregate function and aliases! */
-LEFT JOIN Track /* LEFT JOIN causes all Albums to be returned, even when no matching record in Track table */
-	ON Album.upc=Track.album_upc 
 INNER JOIN Artist 
 	ON Album.artist_id=Artist.id 
 INNER JOIN Genre