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Excepion: mapping cannot have columns in this context(JPA/OpenJPA OneToMany using single table)

 
ping zhang
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Posts: 19
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I want use JPA(provider:OpenJPA) to implement the funciton of category without level limit, and just using one table like the following, and use the annotation:
[b ]@OneToMany(fetch=FetchType.LAZY)
@JoinColumn(name="pid")[/b]

But there alaway exception when using "org.apache.openjpa.jdbc.meta.MappingTool" to generate schema or access data after created schema manually.
If I remove the two line of @OneToMany and @JoinColumn, things go well.

+-------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id | varchar(255) | NO | PRI | NULL | |
| name | varchar(255) | YES | | NULL | |
| pid | varchar(255) | YES | | NULL | |
+-------+--------------+------+-----+---------+-------+


The code:



And the Exception:



Anyone can give me some help? Thanks
 
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