CRUD Operations

The EntityManager offers a large number of methods to perform various queries. We will write methods to insert, fetch, update, and delete data in the PlayerRepository.

merge() method for INSERT and UPDATE queries

The EntityManager offers a merge() method for both INSERT and UPDATE operations. merge() checks if the primary key value is being passed to it or not. If it finds the primary key, it updates the corresponding record. If the primary key is not passed, it generates a value and inserts a new record in the table. The merge() method returns a Player object.

The logic of insertPlayer() and updatePlayer() methods will be the same. The difference lies in the arguments being passed to the merge() method.