Hiberate mapping and java code for a database sequence

Question

I have a sequence in the DB like this

 CREATE SEQUENCE abc
        INCREMENT BY 1
        START WITH 1
 ;

I want a method like

getNextVal(); //My guess is I can fire select abc.nextval from dual

Which returns the next value from the sequence.

How should the .hbm.xml and the code for getNextVal look like. I am new to Hibernate , I tried digging up but have not been able to find a definitive answer.

Is the way of creating sequence optimal.

Alex Gitelman · Accepted Answer · 2011-07-26 06:08:30Z

1

If you need sequence value to generate id, you don't have to worry about getNextVal() as it will be done for you based on your mapping with generated id. Some examples can be found here. And here is some info for annotations.

If you need sequence value for some other reason, you would have to do native SQL query. Something like this

Number val=session.createSQLQuery("select abc.nextval from dual").uniqueResult();

answered Jul 26, 2011 at 6:08

Alex Gitelman

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4 Comments

kal Over a year ago

All the examples tell me that the sequence is used inside a table. How would the mapping with just the sequence look like

Alex Gitelman Over a year ago

As I mentioned, if you don't need it for id (which is most typical use case) then you can use native SQL as I described.

kal Over a year ago

I am guessing that means no mapping is required, is that correct.

Alex Gitelman Over a year ago

It may also be possible to use formula (docs.jboss.org/hibernate/core/3.3/reference/en/html/…). But I never tried that.

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