How to get first name,last name,provider from a email address in Oracle sql

Question

I try to get first name, last name, provider from an email address "ben.ghol@gmail.com" but it doesn't work.

Table emailtable. My code here:

     select 
        SUBSTR(email,1, INSTR(email,'.')-1) as firstname,
        SUBSTR(email,INSTR(email,'.')+1, INSTR(email,'@')-1) as lastname,
        SUBSTR(email,INSTR(email,'@')+1,INSTR(email,'.')-1) as "provider"
        from emailtable;

Answer 1

The third argument for SUBSTR is the length of the substring (and not the position of the end character).

You can use a nested sub-query to find the position of the separators and then use those values in SUBSTR in the outer query:

SELECT SUBSTR(email, 1, name_separator - 1) AS first_name,
       SUBSTR(email, name_separator + 1, at_separator - name_separator - 1)
         AS last_name,
       SUBSTR(email, at_separator + 1, domain_separator - at_separator - 1)
         AS domain
FROM   (
  SELECT email,
         INSTR(email, '.') AS name_separator,
         INSTR(email, '@') AS at_separator,
         INSTR(email, '.', INSTR(email, '@')) AS domain_separator
  FROM   emailtable
)

Which, for the sample data:

CREATE TABLE emailtable ( email ) AS
SELECT 'ben.ghol@gmail.com' FROM DUAL;

Outputs:

FIRST_NAME	LAST_NAME	DOMAIN
ben	ghol	gmail

db<>fiddle here

Answer 2

You can use regexp_substr() :

select regexp_substr(email, '^[^.]+') as firstname,
       regexp_substr(email, '[^.@]+', 1, 2) as lastname,
       regexp_+substr(email, '[^@]+$') as provider
from (select 'ben.ghol@gmail.com' as email from dual) x;

Here is a db<>fiddle.

Answer 3

SUBSTR takes 3 parameters: input string, start position and length of substring.

You appear to be using end position as the 3rd parameter.

You can get the length to use as the 3rd parameter by doing (end position - start position + 1)