Question on REGEXP_INSTR and Regular Expressions!

[vivekmcm]

SELECT REGEXP_INSTR('But, soft! What light through yonder window breaks?', 'l[[:alpha:]]{4}') AS result FROM dual;


 what is 'l[[:alpha:]]{4}' means here

 can anybody explain me full concept of regular expression

[dtech-team]

'l[[:alpha:]]{4}'
 
[:alpha:] - Means any character A to Z or a to z. They are always used inside square brackets in the form [[:alpha:]]
 
l - is a search expression. Means find anything, even if it has no l (0 or 1 times)
 
{4} - means run the RE [[:alpha:]] 4 times.
 
 
To Learn RE, check this tutorial
 

[demonoiduk]

Oracle Database 10g  : Four REGEXP Functions:


REGEXP_LIKE
REGEXP_SUBSTR
REGEXP_REPLACE
REGEXP_INSTR[/b

Read more: http://www.regular-expressions.info/oracle.html