What are the possible values of the Hibernate hbm2ddl.auto configuration and what do they do

Question

I really want to know more about the update, export and the values that could be given to hibernate.hbm2ddl.auto
I need to know when to use the update and w

Answer 1

Although it is quite an old post but as i did some research on the topic so thought of sharing it.

hibernate.hbm2ddl.auto

As per the documentation it can have four valid values:

create | update | validate | create-drop

Following is the explanation of the behaviour shown by these value:

• create :- create the schema, the data previously present (if there) in the schema is lost
• update:- update the schema with the given values.
• validate:- validate the schema. It makes no change in the DB.
• create-drop:- create the schema with destroying the data previously present(if there). It also drop the database schema when the SessionFactory is closed.

Following are the important points worth noting:

• In case of update, if schema is not present in the DB then the schema is created.
• In case of validate, if schema does not exists in DB, it is not created. Instead, it will throw an error:- Table not found:
  In case of create-drop, schema is not dropped on closing the session. It drops only on closing the SessionFactory.

  In case if i give any value to this property(say abc, instead of above four values discussed above) or it is just left blank. It shows following behaviour:

  -If schema is not present in the DB:- It creates the schema

  -If schema is present in the DB:- update the schema.

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