import 'package:drift/drift.dart'; import 'tables/filename.dart'; extension Expressions on MyDatabase { // #docregion emptyCategories Future> emptyCategories() { final hasNoTodo = notExistsQuery( select(todos)..where((row) => row.category.equalsExp(categories.id))); return (select(categories)..where((row) => hasNoTodo)).get(); } // #enddocregion emptyCategories }