Select Page

DB2 Date and Time Data

Author: Craig Mullins | | January 26, 2016

DB2 allows you to add and subtract DATE, TIME, and TIMESTAMP columns. In addition, you can add date and time durations to, or subtract them from, date and time columns. But use date and time arithmetic with care. If you do not understand the capabilities and features of date and time arithmetic, you will likely encounter some problems implementing it.

You can make life easier for yourself by keeping the following rules in mind as you code DB2 date/time arithmetic.

When you issue date arithmetic statements using durations, do not try to establish a common conversion factor between durations of different types. For example, the following two date arithmetic statements are not equivalent:

1997/04/03 – 1 MONTH

1997/04/03 – 30 DAYS

April has 30 days, so the normal response would be to subtract 30 days to subtract one month. The result of the first statement is 1997/03/03, but the result of the second statement is 1997/03/04. In general, use like durations (for example, use months or use days, but not both) when you issue date arithmetic.

Another consideration: if one operand is a date, the other operand must be a date or a date duration. If one operand is a time, the other operand must be a time or a time duration. You cannot mix durations and data types with date and time arithmetic.

If one operand is a timestamp, the other operand can be a time, a date, a time duration, or a date duration. The second operand cannot be a timestamp. You can mix date and time durations with timestamp data types.

Now, what exactly is in that field returned as the result of a date or time calculation? Simply stated, it is a duration. There are three types of durations: date durations, time durations, and labeled durations.

Date durations are expressed as a DECIMAL(8,0) number. The result of subtracting one DATE value from another is a date duration. To be properly interpreted, the number must have the format yyyymmdd, where yyyy represents the number of years, mm the number of months, and dd the number of days.

Time durations are expressed as a DECIMAL(6,0) number. To be properly interpreted, the number must have the format hhmmss, where hh represents the number of hours, mm the number of minutes, and ss the number of seconds. The result of subtracting one TIME value from another is a time duration.

Labeled durations represent a specific unit of time as expressed by a number followed by one of the seven duration keywords: YEARS, MONTHS, DAYS, HOURS, MINUTES, SECONDS, or MICROSECONDS. A labeled duration can only be used as an operand of an arithmetic operator, and the other operand must have a data type of DATE, TIME, or TIMESTAMP. For example:

CURRENT DATE + 3 YEARS + 6 MONTHS

This will add three and a half years to the current date.

This blog post was originally published on Craig Mullins’ blog at: http://db2portal.blogspot.com/2008/11/more-on-db2-date-and-time-data.html

How to Solve the Oracle Error ORA-12154: TNS:could not resolve the connect identifier specified

The “ORA-12154: TNS:could not resolve the connect identifier specified” Oracle error is a commonly seen message for database administrators.

Vijay Muthu | February 4, 2021

Scripting Out SQL Server Logins, Server Role Assignments, and Server Permissions

This blog reviews how you can generate scripts for SQL server logins, role assignments, and server permissions for a smooth migration.

JP Chen | October 1, 2015

How To Fix Log Shipping Failure Errors In SQL Server

Learn how to fix common Log Shipping Failure errors in SQL Server. Includes step-by-step instructions, screenshots, and software script.

Eric Russo | August 10, 2016

Subscribe to Our Blog

Never miss a post! Stay up to date with the latest database, application and analytics tips and news. Delivered in a handy bi-weekly update straight to your inbox. You can unsubscribe at any time.

Work with Us

Let’s have a conversation about what you need to succeed and how we can help get you there.

CONTACT US

Work for Us

Where do you want to take your career? Explore exciting opportunities to join our team.

EXPLORE JOBS