Added playlists tables

src/db/migrations/201707091522_playlists_tables/down.sql

@@ -0,0 +1,2 @@
+DROP TABLE playlists;
+DROP TABLE playlist_songs;

src/db/migrations/201707091522_playlists_tables/up.sql

@@ -0,0 +1,17 @@
+CREATE TABLE playlists (
+	id INTEGER PRIMARY KEY NOT NULL,
+	owner INTEGER NOT NULL,
+	name TEXT NOT NULL,
+	FOREIGN KEY(owner) REFERENCES users(id) ON DELETE CASCADE,
+	UNIQUE(owner, name)
+);
+
+CREATE TABLE playlist_songs (
+	id INTEGER PRIMARY KEY NOT NULL,
+	playlist INTEGER NOT NULL,
+	path TEXT NOT NULL,
+	ordering INTEGER NOT NULL,
+	FOREIGN KEY(path) REFERENCES songs(path) ON DELETE NO ACTION,
+	FOREIGN KEY(playlist) REFERENCES playlists(id) ON DELETE CASCADE,
+	UNIQUE(playlist, ordering)
+);