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

 
 Home
 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
 Analysis
 Design
 Implementation
 Oracle Support


 SQL Tuning
 Security

 Oracle UNIX
 Oracle Linux
 Monitoring
 Remote s
upport
 Remote plans
 Remote
services
 Application Server

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

 Remote S
upport  
 Development  

 Implementation


 Consulting Staff
 Consulting Prices
 Help Wanted!

 


 Oracle Posters
 Oracle Books

 Oracle Scripts
 Ion
 Excel-DB  

Don Burleson Blog 


 

 

 


 

 

 
 

regexp_replace tips

Oracle PL/SQL tips by Boobal Ganesan

This is an excerpt from the book Advanced PL/SQL: The Definitive Reference by Boobal Ganesan.

Syntax:  regexp_replace( source, pattern, replace string, position, occurrence, options)

The source can be a string literal, variable, or column.  The pattern is the expression to be replaced.  The replace string is the text that will replace the matching patterns.  The optional position defines the location to begin searching the source string.  This defaults to 1.  The optional occurrence defines the occurrence of the pattern that you want replaced.  This defaults to 0 (all occurrences).  Setting this to a positive number will result in only that occurrence being replaced.  The matching options are the same.

select
  regexp_replace('We are driving south by south east',
                 'south', 'north')
from dual;

Oracle 10g introduced regular expression functions in SQL with the functions REGEXP_SUBSTR, REGEXP_REPLACE, REGEXP_INSTR and REGEXP_LIKE.

SELECT
   ENAME,
   REGEXP_SUBSTR(ENAME,'DAM') SUBSTR,
   REGEXP_INSTR(ENAME, 'T') INSTR,
   REGEXP_REPLACE(ENAME,'AM','@') REPLACE,
   REGEXP_COUNT(ENAME, 'A') COUNT
FROM
   EMP
WHERE
   REGEXP_LIKE(ENAME,'S');

ENAME      SUBSTR          INSTR REPLACE         COUNT
---------- ---------- ---------- ---------- ----------
SMITH                          4 SMITH               0
JONES                          0 JONES               0
SCOTT                          4 SCOTT               0

ADAMS      DAM                 0 AD@S                2
JAMES                          0 J@ES                1

REPLACE replaces all occurrence of a string. REGEXP_REPLACE has the same behavior by default, but when the fifth parameter, OCCURRENCE, is set to a value greater than zero, the substitution is not global.

SELECT
   REGEXP_REPLACE
   (
      'Programming',
      '([[:alpha:]]+)[[:space:]]([[:alpha:]]+)',
      '\2: \1',
      1,
      1
   )
FROM
   DUAL;

REGEXP_REPLACE('ADVANCEDORACLESQ
--------------------------------
Oracle: Advanced SQL Programming

This function is a successful extension of both the REPLACE and the TRANSLATE function. This function was introduced in the Oracle version 10g, which replaces a specific portion of the source string using a user customized regular expression based search pattern.

                         

The prototype for the REGEXP_REPLACE function is shown below,

 

REGEXP_REPLACE(<Source_string>, <Search_pattern>[, <Replacement_string>[, <Start_position>[, <Match_occurrence>[, <Match_modifiers>]]]])

 

·         Source_string: The string to be searched for.

 

·         Search_pattern: The regular expression pattern that is to be searched for in the source string. This can be a combination of the POSIX and the Perl-influenced metacharacters mentioned in the above section.

 

·         Replacement_string: This is an optional parameter. The matched patterns will be replaced with the Replacement_string in the source string. If not mentioned, the replacement string will be Null.

 

·         Start_position: This is an optional parameter. This determines the position in the source string where the search starts. By default, it is 1, which is the starting position of the source string.

 

·         Match_occurrence: This is an optional parameter. This determines the occurrence of the search pattern. By default, it is 1, which is the first appearance of the search pattern in the string.

 

·         Match_modifiers: This is an optional parameter. This parameter allows us to modify, the matching behavior of the function. The valid range of options is mentioned in the Pattern Matching Modifiers section explained above.

String Removal

The below statement has a mix of numbers, alphabets and punctuations in its source string. The first match pattern selects all the alphabets, the second match pattern selects all the digits and the third match pattern selects all the punctuations, removes them from the source string respectively, and prints the result.

 

WITH

  t AS

  ( SELECT'a0b1c2d3e4f5g6h7i8j9k!l@m#n$o%p^q&r*s(t)u_v+w-x=y[z]' col FROM dual)

SELECT

  regexp_replace(col,'[[:alpha:]]') without_alphabets,

  regexp_replace(col,'[[:digit:]]') without_digits,

  regexp_replace(col,'[[:punct:]]') without_punctuations

FROM

  t;

 

Result:

 

WITHOUT_ALPHABETS

0123456789!@#$%^&*()_+-=[]

 

WITHOUT_DIGITS

abcdefghijk!l@m#n$o%p^q&r*s(t)u_v+w-x=y[z]

 

WITHOUT_PUNCTUATIONS

a0b1c2d3e4f5g6h7i8j9klmnopqrstuvwxyz

Symbol Removal

The below snippet removes all the special symbols from the source string and prints only the readable characters. This query is of much help while saving the emails and documents into the database by removing the unreadable special symbols as a data cleaning process.

 

select regexp_replace('Th∞is St☻ring con♥tains ♫special sy▀mbols','[^a-zA-Z ]') regexp_replace from dual;

 

Result:

This String contains special symbols

Space Removal

The below statement removes the spaces which are present more than once in the source string. This script plays a vital role in removing the unwanted spaces from a document or an email before storing them permanently in the database.

 

select regexp_replace('This    string  contains       more    than  one    spacing       between     the        words','( ){2,}',' ') regexp_replace from dual;

 

Result:

This string contains more than one spacing between the words

Name Rearrange

The below listing re-arranges the last name and the first name from the source string in a user required format for reporting purposes.

 

select regexp_replace('Randy Orton','(.*) (.*)','\2, \1') regexp_replace from dual;

 

Result:

Orton, Randy

Space Addition

The below SQL adds an extra space in between each character from the source string as shown below,

 

select regexp_replace('abcdefghijklmnopqrstuvwxyz','(.)','\1 ') regexp_replace from dual;

 

Result:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Security Measure

The below statement hides the middle portion of a number as a security measure. This process is done by the banking industry during the account-related communication by hiding the middle portion of the credit card, account number, phone number and by the email servers for OTP generation for user confirmation and security check.

 

select regexp_replace('91105434563452345623', '(^[[:digit:]]{4})(.*)([[:digit:]]{4}$)', '\1**********\3') regexp_replace from dual;

 

Result:

9110**********5623

 

Need to learn to program with PL/SQL?  For complete notes on programming in PL/SQL, we recommend the book Advanced PL/SQL: The Definitive Reference by Boobal Ganesan.

This is a complete book on PL/SQL with everything you need to know to write efficient and complex PL/SQL code.

   
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
 
 



 

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 -  2016

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