Multiple Columns in one column - sql

Question

I have a Database which manages my music library, where I store all the id3 Tags in DB tables. The data model looks as followed: http://abload.de/img/modelq5sx3.png
CREATE TABLE Tracks (
Track_ID INTEGER NOT NULL AUTO_INCREMENT,
Title VARCHAR(255),
Track_Year YEAR,
Filename VARCHAR(255),
Track_Length CHAR(5),
Folder_ID INTEGER,
Album_ID INTEGER,
CONSTRAINT PK_Tracks PRIMARY KEY (Track_ID),
UNIQUE Unique_Path (Folder_ID, Filename)
);
CREATE TABLE Artists (
Artist_ID INTEGER NOT NULL AUTO_INCREMENT,
Artist VARCHAR(50),
CONSTRAINT PK_Artists PRIMARY KEY (Artist_ID),
UNIQUE (Artist)
);
CREATE TABLE Albums (
Album_ID INTEGER NOT NULL AUTO_INCREMENT,
Album VARCHAR(100),
AlbumArtist INTEGER,
AlbumCover VARCHAR(100),
CONSTRAINT PK_Albums PRIMARY KEY (Album_ID),
UNIQUE (Album)
);
CREATE TABLE Tracks_Artists (
Artist_ID INTEGER NOT NULL,
Track_ID INTEGER NOT NULL,
CONSTRAINT PK_Tracks_Artists PRIMARY KEY (Artist_ID, Track_ID)
);
So I have tracks,albums and artists in seperate entities with a n:m relation between tracks and artists as a track can be performed by more than one artist and a artist can perform in more than one track. I have done that to search for tracks by artist.
But to make a nice track view I want to have all these artists in one line per track, which I did not manage so far. All I can do is to join over Album, which has one album artist per album:
create or replace view v_c_tracks as SELECT t.traCK_ID,t.title,ar.arTIST,a.album
FROM TRACKS t
join albums a on t.album_id=a.album_id
join artists ar on a.albumartist=ar.artist_id
order by t.title;

Answer 1

You need to join to the track_artists table. Then to get the results on a single row, you need to aggregate by track. The key to bringing the artists together in a list is group_concat():
SELECT t.traCK_ID, t.title, group_concat(ar.artist) as artists, a.album
FROM tracks t join
albums a
on t.album_id = a.album_id join
track_artists ta
on ta.track_id = track.track_id join
artists ar
on ta.artist_id = ar.artist_id
group by t.traCK_ID, t.title, a.album
order by t.title;