Hibernate Automatically creating updating the db tables based on entity classes

Question

I have the following entity class  in Groovy    import javax persistence Entity import javax persistence Id import javax persistence GeneratedValue import javax persistence GenerationType   Entity public class ServerNode       Id    GeneratedValue strategy   GenerationType AUTO    Long id    String firstName   String lastName      and my persistence xml    lt  xml version  1 0  encoding  UTF-8   gt   lt persistence xmlns  http   java sun com xml ns persistence  version  1 0  gt       lt persistence-unit name  NewPersistenceUnit  gt           lt provider gt org hibernate ejb HibernatePersistence lt  provider gt           lt properties gt               lt property name  hibernate connection url  value  jdbc mysql   localhost 3306 Icarus   gt               lt property name  hibernate connection driver class  value  com mysql jdbc Driver   gt               lt property name  hibernate connection username  value  root   gt               lt property name  hibernate connection password  value     gt               lt property name  hibernate archive autodetection  value  class   gt               lt property name  hibernate show sql  value  true   gt               lt property name  hibernate format sql  value  true   gt               lt property name  hbm2ddl auto  value  create   gt           lt  properties gt           lt class gt net interaxia icarus data models ServerNode lt  class gt       lt  persistence-unit gt   lt  persistence gt    and the script   import javax persistence EntityManager import javax persistence EntityManagerFactory import javax persistence Persistence import net interaxia icarus data models ServerNode  def factory   Persistence createEntityManagerFactory  NewPersistenceUnit   def manager   factory createEntityManager    manager getTransaction   begin    manager persist new ServerNode firstName   Test   lastName   Server    manager getTransaction   commit     the database Icarus exists  but currently has no tables  I would like Hibernate to automatically create and or update the tables based on the entity classes  How would I accomplish this

User · Accepted Answer

I don t know if leaving hibernate off the front makes a difference   The reference suggests it should be hibernate hbm2ddl auto  A value of create will create your tables at sessionFactory creation  and leave them intact   A value of create-drop will create your tables  and then drop them when you close the sessionFactory   Perhaps you should set the javax persistence Table annotation explicitly   Hope this helps

User · Answer

You might try changing this line in your persistence xml from   lt property name  hbm2ddl auto  value  create   gt    to    lt property name  hibernate hbm2ddl auto  value  update   gt    This is supposed to maintain the schema to follow any changes you make to the Model each time you run the app   Got this from JavaRanch

User · Answer

Sometimes depending on how the configuration is set  the long form and the short form of the property tag can also make the difference   e g  if you have it like    lt property name  hibernate hbm2ddl auto  value  create   gt    try changing it to    lt property name  hibernate hbm2ddl auto  gt create lt  property gt

User · Answer

You might try changing this line in your persistence xml from   lt property name  hbm2ddl auto  value  create   gt    to    lt property name  hibernate hbm2ddl auto  value  update   gt    This is supposed to maintain the schema to follow any changes you make to the Model each time you run the app   Got this from JavaRanch

User · Answer

There is one very important detail  than can possibly stop your hibernate from generating tables  assuming You already have set the hibernate hbm2ddl auto   You will also need the  Table annotation     Entity  Table name    test entity       public class TestEntity       It has already helped in my case at least 3 times - still cannot remember it     PS  Read the hibernate docs - in most cases You will probably not want to set hibernate hbm2ddl auto to create-drop  because it deletes Your tables after stopping the app

User · Answer

There is one very important detail  than can possibly stop your hibernate from generating tables  assuming You already have set the hibernate hbm2ddl auto   You will also need the  Table annotation     Entity  Table name    test entity       public class TestEntity       It has already helped in my case at least 3 times - still cannot remember it     PS  Read the hibernate docs - in most cases You will probably not want to set hibernate hbm2ddl auto to create-drop  because it deletes Your tables after stopping the app

User · Answer

In support to  thorinkor s answer I would extend my answer to use not only  Table  name    table name   annotation for entity  but also every child variable of entity class should be annotated with  Column name    col name    This results into seamless updation to the table on the go   For those who are looking for a Java class based hibernate config  the rule applies in java based configurations also NewHibernateUtil   Hope it helps someone else

User · Answer

Sometimes depending on how the configuration is set  the long form and the short form of the property tag can also make the difference   e g  if you have it like    lt property name  hibernate hbm2ddl auto  value  create   gt    try changing it to    lt property name  hibernate hbm2ddl auto  gt create lt  property gt

User · Answer

In my case table was not created for the first time without last property listed below    lt properties gt       lt property name  hibernate archive autodetection  value  class   gt       lt property name  hibernate show sql  value  true   gt       lt property name  hibernate format sql  value  true   gt       lt property name  hbm2ddl auto  value  create-drop   gt       lt  -- without below table was not created -- gt       lt property name  javax persistence schema-generation database action  value  drop-and-create    gt   lt  properties gt    used Wildfly s in-memory H2 database

User · Answer

In my case table was not created for the first time without last property listed below    lt properties gt       lt property name  hibernate archive autodetection  value  class   gt       lt property name  hibernate show sql  value  true   gt       lt property name  hibernate format sql  value  true   gt       lt property name  hbm2ddl auto  value  create-drop   gt       lt  -- without below table was not created -- gt       lt property name  javax persistence schema-generation database action  value  drop-and-create    gt   lt  properties gt    used Wildfly s in-memory H2 database

User · Answer

In support to  thorinkor s answer I would extend my answer to use not only  Table  name    table name   annotation for entity  but also every child variable of entity class should be annotated with  Column name    col name    This results into seamless updation to the table on the go   For those who are looking for a Java class based hibernate config  the rule applies in java based configurations also NewHibernateUtil   Hope it helps someone else

User · Answer

You might try changing this line in your persistence xml from   lt property name  hbm2ddl auto  value  create   gt    to    lt property name  hibernate hbm2ddl auto  value  update   gt    This is supposed to maintain the schema to follow any changes you make to the Model each time you run the app   Got this from JavaRanch

User · Answer

In applicationContext xml file    lt bean id  entityManagerFactoryBean  class  org springframework orm jpa LocalContainerEntityManagerFactoryBean  gt         lt property name  dataSource  ref  dataSource    gt         lt  -- This makes  META-INF persistence xml is no longer necessary -- gt         lt property name  packagesToScan  value  com howtodoinjava demo model    gt         lt  -- JpaVendorAdapter implementation for Hibernate EntityManager             Exposes Hibernate s persistence provider and EntityManager extension interface -- gt         lt property name  jpaVendorAdapter  gt            lt bean class  org springframework orm jpa vendor HibernateJpaVendorAdapter    gt         lt  property gt         lt property name  jpaProperties  gt            lt props gt               lt prop key  hibernate hbm2ddl auto  gt update lt  prop gt               lt prop key  hibernate dialect  gt org hibernate dialect MySQL5Dialect lt  prop gt            lt  props gt         lt  property gt      lt  bean gt

User · Answer

You might try changing this line in your persistence xml from   lt property name  hbm2ddl auto  value  create   gt    to    lt property name  hibernate hbm2ddl auto  value  update   gt    This is supposed to maintain the schema to follow any changes you make to the Model each time you run the app   Got this from JavaRanch

User · Answer

In applicationContext xml file    lt bean id  entityManagerFactoryBean  class  org springframework orm jpa LocalContainerEntityManagerFactoryBean  gt         lt property name  dataSource  ref  dataSource    gt         lt  -- This makes  META-INF persistence xml is no longer necessary -- gt         lt property name  packagesToScan  value  com howtodoinjava demo model    gt         lt  -- JpaVendorAdapter implementation for Hibernate EntityManager             Exposes Hibernate s persistence provider and EntityManager extension interface -- gt         lt property name  jpaVendorAdapter  gt            lt bean class  org springframework orm jpa vendor HibernateJpaVendorAdapter    gt         lt  property gt         lt property name  jpaProperties  gt            lt props gt               lt prop key  hibernate hbm2ddl auto  gt update lt  prop gt               lt prop key  hibernate dialect  gt org hibernate dialect MySQL5Dialect lt  prop gt            lt  props gt         lt  property gt      lt  bean gt

[java] Hibernate: Automatically creating/updating the db tables based on entity classes

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