How to remove special characters in a string using Oracle Sql Query

How to remove special characters in a string using Oracle Sql Query?

SELECT     REGEXP_REPLACE('Th♥is∞ is a dem☻o of REGEXP_♫REPLACE function','[^a-z_A-Z ]') FROM     dual;

The following is the output result.

This is a demo of REGEXP_REPLACE function.
This query is useful mainly for data cleaning purpose.

How to remove redundant spaces in a string using Oracle SQL Query?

SELECT

  regexp_replace(

  'This line    contains    more      than one   spacing      between      words'

  , '( ){2,}', ' ' ) regexp_replace

FROM

  dual;

Output:

This line contains more than one spacing between words