Why is the notion of a owning side necessary: The idea of a owning side of a bidirectional relation comes from the fact that in relational databases there are no bidirectional relations like in the case of objects. In databases we only have unidirectional relations – foreign keys. What is the reason for the name … Read more
SQLAlchemy introduced that in version 1.0.0: Bulk operations – SQLAlchemy docs With these operations, you can now do bulk inserts or updates! For instance, you can do: s = Session() objects = [ User(name=”u1″), User(name=”u2″), User(name=”u3″) ] s.bulk_save_objects(objects) s.commit() Here, a bulk insert will be made.
Nabeel’s answer covers a lot of details and is helpful, but I found it confusing to follow. Since this is currently the first Google result for this issue, adding my understanding of it for future people that find this question: Running .execute() As OP and Nabell Ahmed both note, when executing a plain SELECT * … Read more
It’s not generally correct that you can “remove an item from a database” with both methods. To be precise it is like so: ObjectContext.DeleteObject(entity) marks the entity as Deleted in the context. (It’s EntityState is Deleted after that.) If you call SaveChanges afterwards EF sends a SQL DELETE statement to the database. If no referential … Read more
SQLAlchemy’s ORM is meant to be used together with the SQL layer, not hide it. But you do have to keep one or two things in mind when using the ORM and plain SQL in the same transaction. Basically, from one side, ORM data modifications will only hit the database when you flush the changes … Read more
Here is how you do in Eloquent $users = User::whereIn(‘id’, array(1, 2, 3))->get(); And if you are using Query builder then : $users = DB::table(‘users’)->whereIn(‘id’, array(1, 2, 3))->get();
There are arguments for both, but most of them stem from certain user requirements “what if you need to add logic for”, or “xxxx breaks encapsulation”. However, nobody has really commented on the theory, and given a properly reasoned argument. What is Hibernate/JPA actually doing when it persists an object – well, it is persisting … Read more
That limitation comes down to the fact that eventually it has to translate that query to SQL and SQL has a SELECT TOP (in T-SQL) but not a SELECT BOTTOM (no such thing). There is an easy way around it though, just order descending and then do a First(), which is what you did. EDIT: … Read more
Alternatively, you can use one query with a lookup: var lookup = new Dictionary<int, Course>(); conn.Query<Course, Location, Course>(@” SELECT c.*, l.* FROM Course c INNER JOIN Location l ON c.LocationId = l.Id “, (c, l) => { Course course; if (!lookup.TryGetValue(c.Id, out course)) lookup.Add(c.Id, course = c); if (course.Locations == null) course.Locations = new List<Location>(); … Read more
While the accepted answer isn’t technically wrong, it doesn’t answer the original question nor the follow up question in the comments, which was what I came here looking for. But I figured it out, so here goes. If you want to find all Posts that have Users (and only the ones that have users) where … Read more