What database management systems have you used in your projects?

In iOS projects, I most often used the following database management systems:

• Core Data — Apple's framework for managing object data models, which allows saving and retrieving data using an ORM approach.
• SQLite — a relational database that can be accessed directly through SQL queries. Often used via wrappers, such as FMDB.
• Realm — a modern mobile database that is easy to use and efficient for storing objects.

Example of using Realm:

import RealmSwift

class Dog: Object {
    @objc dynamic var name = ""
    @objc dynamic var age = 0
}

let realm = try! Realm()

let dog = Dog()
dog.name = "Rex"
dog.age = 3

try! realm.write {
    realm.add(dog)
}