rem: return transaction -> transaction_id;
add: if ( transaction -> transaction_id ) return transaction -> transaction_id; else return "";
context: gchar *gsb_data_transaction_get_transaction_id ( gint no_transaction ){    struct_transaction *transaction;    transaction = gsb_data_transaction_get_transaction_by_no ( no_transaction);    if ( !transaction )	return NULL;    return transaction -> transaction_id;}