[英]JPA or Hibernate to generate a (non primary key) column value, not starting from 1
[英]How generate the primary key from XML in Hibernate?
我有一个用户类:
public class User{
private Long userId;
}
我在xml中使用它:
<id name="userId" type="long" unsaved-value="null">
<column name="USER_ID" not-null="true" />
<generator class="native" />
</id>
但是,当我尝试保存用户对象而不将userId分配给对象时,出现以下错误:
Caused by: java.sql.SQLException: Field 'USER_ID' doesn't have a default value
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:957)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3878)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3814)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2478)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2625)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2551)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1861)
at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2073)
at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2009)
at com.mysql.jdbc.PreparedStatement.executeLargeUpdate(PreparedStatement.java:5094)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1994)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208)
... 22 more
我希望Hibernate为我生成ID。 我在这里想念什么?
您需要为USER_ID列设置autoincrement
ALTER TABLE users ADD USER_ID INT UNSIGNED NOT NULL AUTO_INCREMENT;
native
指令意味着您的数据库负责生成ID。 由于未在数据库侧设置策略来生成ID,因此出现异常java.sql.SQLException: Field 'USER_ID' doesn't have a default value
。
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