Programmer blog

One comes to a task that has to do with counting items in a database. We will describe the right approach here. Despite being so obvious I did not find much of the docs for junior developers to watch and learn. Here is a sample task and solution: Let's assume we have a model like so: class Cycle (db.Model): id = db.Column(db.Integer, primary_key= True ) object_id = db.Column(db.String, nullable= False ) Sample date populated into it will be: { id : 1 , object_id: 'unique1' }, { id : 2 , object_id: 'unique1' }, { id : 3 , object_id: 'unique2' }, { id : 4 , object_id: 'unique2' }, { id : 5 , object_id: 'unique2' }, { id : 6 , object_id: 'unique3' } We need to count unique model instances with same  object_id . To achieve this relatively simple task one would go straightforward. E.g. Fetch all the Cycle instances with a simple query and then

Despite using console most of the time I have a preference to edit PostgreSQL databases through UI. Especially when it comes to remote side. Usually one can access this through  $ psql  command. However this tends to writing raw SQL queries and a lot of typing in overall. Here is a way to do it with UI. First one needs to make a tunnel.Command is fairly simple: ssh - fNg - L 5555 : localhost : 5432 { username } @ { host . com } One has a tunnel afterwards. This command opens a SSH connection in the background mapping your local port 5555 to your server’s port 5432 (Postgres’ default port). To understand one can observe the meaning of the flags via  $ man ssh  to see what each of these flags doing.  It can be accessed via localhost tools like pgAdmin4 at localhost and port 5555 DB config would look like so: