allow on artist to have multiple urls

sql/create_tables.sql

@@ -24,7 +24,6 @@ AS $$
 		website_id integer,
 		artist_id integer,
 		CONSTRAINT aw_url UNIQUE(url),
-		CONSTRAINT aw_folder_path UNIQUE(folder_path),
 		CONSTRAINT aw_artist FOREIGN KEY (artist_id) REFERENCES artist (ID),
 		CONSTRAINT aw_website FOREIGN KEY (website_id) REFERENCES website (ID)
 	);

sql/insert_url_with_custom_artist.sql

@@ -16,18 +16,14 @@ BEGIN
 	PERFORM * FROM artist a
 	WHERE a.name = in_artist_name;
 
-    IF FOUND THEN
-        RAISE EXCEPTION 'artist already exists';
+    IF NOT FOUND THEN
+		INSERT INTO artist (name) VALUES (in_artist_name);
     END IF;
 
-	INSERT INTO artist_website (url) VALUES (in_url);
-	INSERT INTO artist (name) VALUES (in_artist_name);
-
 	SELECT artist.id INTO temp_artist_id FROM artist
 	WHERE artist.name = in_artist_name;
 
-	UPDATE artist_website SET artist_id = temp_artist_id 
-	WHERE url = in_url;
+	INSERT INTO artist_website (url, artist_id) VALUES (in_url, temp_artist_id);
 
 	SELECT * INTO ret_value FROM set_website_name(in_url);
 	IF ret_value <> 0 THEN