spring boot jpa insert data on startup if not exist code example

Example: spring import sql

-- You can simply create a data.sql file in your src/main/resources folder 
-- and it will be automatically executed on startup. 
-- In this file you just add some insert statements, eg.:

INSERT INTO users (username, firstname, lastname) VALUES
  ('lala', 'lala', 'lala'),
  ('lolo', 'lolo', 'lolo');
  
-- If you're using Spring boot 2, database initialization only works for 
-- embedded databases (H2, HSQLDB, ...). If you want to use it for other 
-- databases as well, you need to change the 
-- spring.datasource.initialization-mode property:

spring.datasource.initialization-mode=always