func (c *Cluster) ImageUploadedAt(id int, uploadedAt time.Time) error {
	err := exec(c.db, "UPDATE images SET upload_date=? WHERE id=?", uploadedAt, id)
	return err
}
func (c *Cluster) ImageUploadedAt(id int, uploadedAt time.Time) error {
	err := exec(c.db, "UPDATE images SET upload_date=? WHERE id=?", uploadedAt, id)
	return err
}
// ImageUploadedAt updates the upload_date column and an image row.