SOLUTION TO SOLVE THE ORACLE QEQUENCE

If the sequence does not work in ejb, then try to change the id data type to Long firstly, then add the following code upon the id field.

@Id
@SequenceGenerator(name="COMMANDITEM_COMMANDID_GENERATOR", sequenceName="CMDSEQUENCE", allocationSize=1)
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="COMMANDITEM_COMMANDID_GENERATOR")
private long commandid;