As per the JPA specification, COUNT returns a Long: 4.8.4 Aggregate Functions in the SELECT Clause The result of a query may be the result of an aggregate function applied to a path expression. The following aggregate functions can be used in the SELECT clause of a query: AVG, COUNT, MAX, MIN, SUM. For all … Read more
I’ve been working with django for a while now and I have had a pretty rough time figuring out the table joins, but I think I finally understand and I would like to pass this on to others so they may avoid the frustration that I had with it. Consider the following model.py: class EventsMeetinglocation(models.Model): … Read more
You are probably looking for select_related, which is the natural way to achieve this: pubs = publication.objects.select_related(‘country’, ‘country_state’, ‘city’) You can check the resulting SQL via str(pubs.query), which should result in output along the following lines (the example is from a postgres backend): SELECT “publication”.”id”, “publication”.”title”, …, “country”.”country_name”, … FROM “publication” INNER JOIN “country” ON … Read more
In Hibernate, natural keys are often used for lookups. You will have an auto-generated surrogate id in most cases. But this id is rather useless for lookups, as you’ll always query by fields like name, social security number or anything else from the real world. When using Hibernate’s caching features, this difference is very important: … Read more
The reason that Swift doesn’t currently support static stored properties on generic types is that separate property storage would be required for each specialisation of the generic placeholder(s) – there’s more discussion of this in this Q&A. We can however implement this ourselves with a global dictionary (remember that static properties are nothing more than … Read more
You can see the docs here that explains the @Column decorator. In @Column there is an option called type -> here is where you specify which type of date you want to store for that specific column. More on column types here. For example (using PostgreSQL): @Column({ type: ‘date’ }) date_only: string; @Column({ type: ‘timestamptz’ … Read more
Eloquent is Laravel’s implementation of Active Record pattern and it comes with all its strengths and weaknesses. Active Record is a good solution for processing a single entity in CRUD manner – that is, create a new entity with filled properties and then save it to a database, load a record from a database, or … Read more
Short answer: No, you won’t have entity in the database. Longer answer: hibernate is smart enough not to send insert/updates to the DB until it knows if the transaction is going to be committed or rolled back (although this behavior can be changed by setting a different FlushMode), in your case by calling flush you … Read more
Manually opening a connection is not “bad practice”; dapper works with open or closed connections as a convenience, nothing more. A common gotcha is people having connections that are left open, unused, for too long without ever releasing them to the pool – however, this isn’t a problem in most cases, and you can certainly … Read more