What are the basic principles of Object-Relational Mapping (ORM)?

The basic principles of Object-Relational Mapping (ORM) involve mapping object-oriented programming objects to relational databases.

Object-Relational Mapping (ORM) is a programming technique that allows developers to interact with their database like they would with SQL. In other words, the data in the database is treated as objects, which eliminates the need for most of the data-access code that developers usually need to write. ORM is a bridge between the object-oriented and relational worlds, and this bridge is built on several key principles.

The first principle is the mapping of classes to tables. In ORM, each class corresponds to a table in the database. The instances of the class are rows in the table, and the attributes of the class are the columns in the table. This mapping allows developers to work with a more intuitive and high-level abstraction of the data.

The second principle is the support for CRUD operations. ORM systems provide methods for creating, reading, updating, and deleting records in the database, which correspond to the CRUD operations. These methods are usually provided by the ORM system in a way that is independent of the specific database system being used.

The third principle is the support for queries. ORM systems provide a way to query the database, usually in a way that is independent of the specific database system being used. This allows developers to write queries in a high-level, database-independent way.

The fourth principle is the support for transactions. Transactions are a way to ensure that multiple operations on the database happen all at once or not at all. This is important for maintaining the integrity of the data in the database.

The fifth principle is the support for associations. Associations are relationships between tables in the database, such as one-to-one, one-to-many, and many-to-many relationships. ORM systems provide a way to work with these associations in a high-level, object-oriented way.

In conclusion, ORM is a powerful tool that can greatly simplify the task of working with databases in object-oriented programming. By understanding the principles of ORM, developers can make the most of this tool and write more efficient, maintainable code.