EnterpriseDB: INTERVAL Oracle Tips by Burleson Consulting

An interval is a period of time, like the time it takes you to leave your house and the time it takes you to drive to work is an interval of time.  An interval is the difference between a starting point in time and an ending point in time (my, how 4th dimensional!).

Intervals also (like a timestamp) accept an optional precision of 1-6.  That precision determines the granularity of the unit chosen.  The available units of time are:  second, minute, hour, day, week, month, year, decade, century, or millennium.

A date, let's say 01-JAN-2006 added to INTERVAL '1 YEAR', DATE '01-JAN-2006' + INTERVAL '1 YEAR', would equal 01-JAN-2007.  That same date added to INTERVAL '6 MONTHS' would equal 01-JUL-2006.

The uses of INTERVAL are somewhat limited.  I have rarely needed them and had they not been available, I could have made do with a NUMBER field or a DATE field.  I would recommend that you not use INTERVAL unless migrating an application that uses it already.

There are no synonyms for interval.

CREATE TABLE date_table (
  date_field DATE,
  ts_field   TIMESTAMP(6),
  int_field  INTERVAL );

We can insert some values: 

INSERT INTO date_table ( date_field, ts_field, int_field )
  VALUES (to_date('01-JAN-2007 12:33:54', 'DD-MON-YYYY HH24:MI:SS'),
          to_timestamp('01-JAN-2007 12:33:54.123456',
                       'DD-MON-YYYY HH24:MI:SS.us'),
          INTERVAL '1 Year' );

* EnterpriseDB does not support the .ff fractional seconds syntax that Oracle supports.  It does not produce an error but only returns a 0.  Use .ms for milliseconds and .us for microsends. 

And we can select those values back out:

SELECT date_field, ts_field, int_field
  FROM date_table; 

edb=# CREATE TABLE date_table (
edb(#   date_field DATE,
edb(#   ts_field   TIMESTAMP(6),
edb(#   int_field  INTERVAL );

CREATE TABLE

edb=# INSERT INTO date_table ( date_field, ts_field, int_field )edb-#   VALUES (to_date('01-JAN-2007 12:33:54', 'DD-MON-YYYY HH24:MI:SS'),
edb(#           to_timestamp('01-JAN-2007 12:33:54.123456',
edb(#                        'DD-MON-YYYY HH24:MI:SS.us'),
edb(#           INTERVAL '1 Year' );
INSERT 0 1
edb=# SELECT date_field, ts_field, int_field
edb-#   FROM date_table;

     date_field     |         ts_field          | int_field
--------------------+---------------------------+-----------
 01-JAN-07 12:33:54 | 01-JAN-07 12:33:54.123456 | @ 1 year

(1 row)

edb=#

Binary Data

Binary data is data that is not interpreted by the database.  For example, a string of data, let's use "Lewis" as an example, is stored as 1s and 0s on the physical disk but the database interprets those 1s and 0s so that it comes out "Lewis".  If you switched to a different language, you could translate that word into its foreign language counterpart.  This is known as having a locale.

A digital image is a binary file.  The data would be stored as 1s and 0s and the database would never try to interpret what those 1s and 0s mean.  If you switched to another language, it would still just be 1s and 0s.  Binary data has no locale.

This is an excerpt from the book "EnterpriseDB: The Definitive Reference" by Rampant TechPress.