Question

I’m brand new to Derby (and basically databases in general) and am trying to get my feet wet with Derby via Eclipse using Java.

What I’m trying to do is generate a report of all entries currently in the Derby database from the last 30 seconds since the report has been generated.

I managed to get what I wanted in MySQL with the following:

SELECT * FROM table WHERE datetime > (now() – interval 30 second)

Is there an equivalent or similar functionality in Derby?

Answer 1

Unfortunately Derby does not support standard (ANSI) SQL date arithmetics. You need to use the JDBC escape functions:

c:\db-derby-10.8.2.2\bin>ij
ij version 10.8
ij> connect 'jdbc:derby:c:/temp/sotest';
ij> create table foo (datetime timestamp);
0 rows inserted/updated/deleted
ij> insert into foo values (current_timestamp);
1 row inserted/updated/deleted
ij> commit;
ij> select *
from foo
where datetime > {fn timestampadd(SQL_TSI_DAY, -10, current_timestamp)};
> > DATETIME
-----------------------------
2012-06-10 12:32:48.859

1 row selected
ij>

For a complete list of functions see the Reference Manual: http://db.apache.org/derby/docs/10.8/ref/rrefjdbc88908.html