Tags: java | persistence | spring

Automatically generated ID's are very handy, since you don't have to create the ID yourself and don't need a second roundtrip to the database as you would when you use a sequence

Example

CREATE TABLE AUTHOR (
  ID BIGINT NOT NULL GENERATED ALWAYS AS IDENTITY,
  NAME VARCHAR(100) NOT NULL,
  PRIMARY KEY(ID));

CREATE TABLE BOOK (
  ID BIGINT NOT NULL GENERATED ALWAYS AS IDENTITY,
  TITLE VARCHAR(100) NOT NULL,
  AUTHOR_ID BIGINT NOT NULL,
  PRIMARY KEY(ID));

When you insert a new book into the database, it will generate the ID automatically. However, when you need to insert multiple records with foreign key relations, like a author and a book record, where the author_id is the generated id of the author record, you need to determine the generated id.

---

Add this page to your favorite Social Bookmarking websites