Object-Relational Mapping (ORM) is a technique that lets you query and manipulate data from a database using an object-oriented paradigm. When talking about ORM, most people are referring to a library that implements the Object-Relational Mapping technique,
greenDAO is an open source Android ORM making development for SQLite databases fun again. It relieves developers from dealing with low-level database requirements while saving development time. SQLite is an awesome embedded relational database. Still, writing SQL and parsing query results are quite tedious and time-consuming tasks. greenDAO frees you from these by mapping Java objects to database tables (called ORM, “object/relational mapping”). This way you can store, update, delete, and query for Java objects using a simple object oriented API. The advantages are
Maximum performance (probably the fastest ORM for Android)
Easy to use powerful APIs covering relations and joins
Minimal memory consumption
Database encryption: greenDAO supports SQLCipher to keep your user’s data safe
Small library size (<100KB) to keep your build times low and to avoid the 65k method limit
SugarORM is an ORM built only for Android. It comes with an API which is both simple to learn and simple to remember. It creates necessary tables itself, gives you a simple methods of creating one-to-one and one-to-many relationships, and also simplifies CRUD by using only 3 functions, save(), delete() and find() (or findById()).
Realm Mobile Database is an alternative to SQLite and Core Data. Thanks to its zero-copy design, Realm Mobile Database is much faster than an ORM, and often faster than raw SQLite. Get started in minutes, not hours. The Realm Mobile Platform is a next-generation data layer for applications. Realm is reactive, concurrent, and lightweight, allowing you to work with live, native objects.