that increments the maximum value of a given Derby table
with the equivalent of an auto-increment column. Note: If you use this class, your Derby key
column should NOT
be defined as an IDENTITY column, as the sequence table does the job.
The sequence is kept in a table. There should be one sequence table per
table that needs an auto-generated key.
Derby requires an additional column to be used for the insert since it is impossible
to insert a null into the identity column and have the value generated. This is solved by
providing the name of a dummy column that also must be created in the sequence table.
create table tab (id int not null primary key, text varchar(100));
create table tab_sequence (value int generated always as identity, dummy char(1));
insert into tab_sequence (dummy) values(null);
If "cacheSize" is set, the intermediate values are served without querying the
database. If the server or your application is stopped or crashes or a transaction
is rolled back, the unused values will never be served. The maximum hole size in
numbering is consequently the value of cacheSize.
Since Derby supports the JDBC 3.0
it is recommended to use IDENTITY columns directly in the tables and then utilizing
when calling the with the
update(PreparedStatementCreator psc, KeyHolder generatedKeyHolder)
method of the
Thanks to Endre Stolsvik for the suggestion!