code: func (cert *Certificate) Select(tx *sql.Tx) error {
  	row := tx.QueryRow(`SELECT aki, not_before, not_after, raw FROM certificates WHERE ski=? and serial=?`, cert.SKI, cert.Serial)
  	err := row.Scan(&cert.AKI, &cert.NotBefore, &cert.NotAfter, &cert.Raw)
  	if err != nil {
  		return err
  	}
  
  	cert.cert, err = x509.ParseCertificate(cert.Raw)
  	return err
  }
docs: // Select requires the SKI and Serial fields to be filled in.