java - JPA and toplink create-table on if they don't already exist? -

It seems that JPA is something that asks a lot of questions.

Adding it

  & lt; Property Name = "toplink.ddl-Generation" Value = "Create-Table" />  

My JPA applications always make tables on the running, which creates exceptions in the presence of tables already, I would like to test the JPA whether tables already existed. And if they have not made them, then I could not find any value for the above property.

So if I turn it off, then what's the way to tell JPA at some points to create all the tables?

Here I get an update exception

  Internal Exception: com.mysql.jdbc.exceptions.jdbc4 MySQLSyntaxErrorException: The table 'tag' already exists Error code: 1050 calls : Create a Call Tab (ID start AUTO_INCREMENT is not a faucet, name VARCHAR (255), Occurrence Injuger, Primary Key (ID))  

MySQLSyntaxErrorException?! Now there is no option to update the existing table according to topling

I'm sure that if I trust it I can configure Toplank to generate a SQL script to do exactly what you need to do to manually execute all the tables. File names and locations can be configured like this:

  & lt; Property name = "toplink.ddl-generation" value = "create-tables" /> & Lt; Property Name = "toplink.ddl-generation.output-mode" value = "sql-script" /> & Lt; Property Name = "toplink.create-ddl-jdbc-file-name" value = "createDDL.sql" /> & Lt; Property Name = "toplink.drop-ddl-jdbc-file-name" value = "dropDDL.sql" /> & Lt; Property name = "toplink.application-location" value = "/ tmp" />