How do I add a column to a JPA entity, and still keep my data? -

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during development of jpa application, added field "type" entity. caused application fail start with

caused by: exception [eclipselink-4002] (eclipse persistence services - 2.0.2.v20100323-r6872): org.eclipse.persistence.exceptions.databaseexception internal exception: java.sql.sqlsyntaxerrorexception: column 't1.type' either not in table in list or appears within join specification , outside scope of join specification or appears in having clause , not in group list. if create or alter table  statement 't1.type' not column in target table. error code: -1

during selection.

is there way alter table on startup, match current entity definitions? notice when app starts calls create table each table, fails , carries on.

in past when i've added fields entities delete database , start again. ok me if want add field entry when developing next release of software, how upgrade clients without losing there data?

thanks in advance - phil.

generally speaking, database generators of jpa providers not reliable creating , updating production databases. suppose in version 1 had field named name user entity , in version 2 replace firstname , lastname. in such cases db generator unable migrate schema correctly.

in other words, jpa provider's automatic db generation useful development , not production.

instead, can consider using database migration tool liquibase.

having said that, while eclipselink not support way updating, rather re-creating, tables using eclipselink.ddl-generation property, other jpa providers (e.g. hibernate) support updating of database tables. however, can not relied on production use fail in cases given example.


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