Remove non-album artist_ids from the DB

db/migration/20211105162746_remove_invalid_artist_ids.go

@@ -0,0 +1,22 @@
+package migrations
+
+import (
+	"database/sql"
+
+	"github.com/pressly/goose"
+)
+
+func init() {
+	goose.AddMigration(upRemoveInvalidArtistIds, downRemoveInvalidArtistIds)
+}
+
+func upRemoveInvalidArtistIds(tx *sql.Tx) error {
+	_, err := tx.Exec(`
+update media_file set artist_id = '' where not exists(select 1 from artist where id = artist_id)
+`)
+	return err
+}
+
+func downRemoveInvalidArtistIds(tx *sql.Tx) error {
+	return nil
+}