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Create database tables: student

  • Hibernate/JPA CRUD (9)
  • Previously, we created database tables by running a SQL script
  • JPA/Hibernate provides an option to automagically create database tables
  • Creates tables based on Java code with JPA/Hibernate annotations
  • Useful for development and testing

Configuration

  • In Spring Boot configuration file:application.properties
# Add logging configs to display SQL statements  

# Log SQL statements  
logging.level.org.hibernate.SQL=debug  

# Log values for SQL statement  
logging.level.org.hibernate.orm.jdbc.bind=trace

# # Configure JPA/Hibernate to auto create the tables
spring.jpa.hibernate.ddl-auto=create
-> DROP & CREATE evey time
  • When you run your app, JPA/Hibernate will drop tables then create them
  • Based on the JPA/Hibernate annotations in your Java code

Creating Tables based on Java Code

Configuration - application.properties

spring.jpa.hibernate.ddl-auto=PROPERTY-VALUE
Property Value Property Description
none No action will be performed
create-only Database tables are only created
drop Database tables dropped (When database tables are dropped, all data is lost)
create Database tables are dropped followed by database tables creation
create-drop Database tables are dropped followed by database tables creation. On application shutdown, drop the database tables
validate Validate the database tables schema
update Update the database tables schema

Basic Projects

  • For basic projects, can use auto configuration 
    spring.jpa.hibernate.ddl-auto=create
  • Database tables are dropped first and then created from scratch
    • Note: When database tables are dropped, all data is lost
  • If you want to create tables once.. and then keep data, use:update 
    spring.jpa.hibernate.ddl-auto=update
  • However, will ALTER database schema based on latest code updates
  • Be VERY careful here … only use for basic projects

Warning

spring.jpa.hibernate.ddl-auto=create
  • Don’t do this on Production databases !!
  • You don’t want to drop your Production data
    • All data is deleted!!!
  • Instead for Production, you should have DBAs run SQL scripts

Use Case

spring.jpa.hibernate.ddl-auto=create
  • Automatic table generation is useful for
    • Database integration testing with in-memory databases
    • Basic, small hobby projects

Recommendation

  • In general, I don’t recommend auto generation for enterprise, real-time projects
    • You can VERY easily drop PRODUCTION data if you are not careful
  • I recommend SQL scripts
    • Corporate DBAs prefer SQL scripts for governance and code review
    • The SQL scripts can be customized and fine-turned for complex database designs
    • The SQL scripts can be version-controlled
    • Can also work with schema migration tools such as Liquibase and Flyway

개인프로젝트가 아닌 이상 웬만하면 SQL scripts 사용하는게 여러모로 좋다.

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