Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 E-mail Us
 Oracle Articles
New Oracle Articles

 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog

 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Oracle Support

 SQL Tuning

 Oracle UNIX
 Oracle Linux
 Remote s
 Remote plans
 Application Server

 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S


 Consulting Staff
 Consulting Prices
 Help Wanted!


 Oracle Posters
 Oracle Books

 Oracle Scripts

Don Burleson Blog 







Difference between decode and case tips

Oracle Database Tips by Donald BurlesonApril 13, 2016

Question: What is the difference between the decode and case operators in Oracle SQL?  Can you illustrate the difference between case and decode with an example?

Answer:  The difference between decode and case are straightforward.  While the decode operator has been around since the earliest days of Oracle, the case operator was introduced in Oracle 8.1.6.

While d3code and case can be used interchangeably, the decode is more powerful because decode can change SQL results.  See my notes on the  decode function.  The case statement is used for conditional power in SQL statements.  See my notes on the case clause.

The case function is a much better option because case is:

- More flexible than DECODE
- Easier to read
- ANSI-compatible

However, CASE is essentially a better implementation of DECODE so the reasons for using either are similar.

Compare decode and case functions

The most powerful of all of the BIFs are the decode and case functions.  The decode and case functions are used within the Oracle database to transform data values for one value to another. 
One of the most amazing features of the case the decode statements is that they allow us to create an index on data column values that do not exist in the database.
Oracle started with the decode statement and later refined it in Oracle9i, morphing it into the case statement.
Let's take a look at how the decode statement works.  The decode statement was developed to allow us to transform data values at retrieval time.  For example, say we have a column named REGION, with values of N, S, W and E.  When we run SQL queries, we want to transform these values into North, South, East and West.  Here is how we do this with the decode function:
   decode (
Note that decode starts by specifying the column name, followed by set of matched-pairs of transformation values.  At the end of the decode statement we find a default value.  The default value tells decode what to display if a column values is not in the paired list.
We can also use the decode statement to count the number of distinct values within a data column.
The decode function is considered the most powerful function in Oracle. Oracle 8i release introduced the CASE expression. The CASE expression can do all that DECODE does plus lot of other things including IF-THEN analysis, use of any comparison operator and checking multiple conditions, all in a SQL query itself. Moreover, using the CASE function, multiple conditions provided in separate SQL queries can be combined into one, thus avoiding multiple statements on the same table.



Oracle Training from Don Burleson 

The best on site "Oracle training classes" are just a phone call away! You can get personalized Oracle training by Donald Burleson, right at your shop!

Oracle training

  Oracle consulting and training


Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


Copyright © 1996 -  2020

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.



Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster