I have a database called dx_data. There is a field in it called dx_dati that is a date and time field. As a user enters a record in the database, this field is stamped with the system date & time.
What I require is a query to list all the records in the database that are within 30 minutes of the current system time. I am using a Postgres database (fairly new version).

select to_char(sysdate,'DD-MON-YYYY HH:MI') normal_time,to_char(sysdate-1/48,'DD-MON-YYYY HH:MI') time_minus_30_mins from dual;

TO_CHAR(SYSDATE,' TO_CHAR(SYSDATE-1
----------------- -----------------
06-JAN-2004 10:40 06-JAN-2004 10:10

SELECT * FROM dx_dati WHERE DATE_FIELD => sysdate-1/48

THIS WILL RETURN ALL RECORDS TIMESTAMPED OVER THE PASS HALF HOUR

Unfortunately, the poster is using Postgres, not Oracle.

Okay, I can see where this may be a problem with postgres. Not sure why, but maybe there is a simpler work around.
Would it be easier to have a query where I get a listing of the most recent 25 entries in the database?