使用 Reg_exp 从电子邮件预言机中提取名字和姓氏

Question

How to extract First_name & last_name from email using oracle REGEXP_SUBSTR,

Email: susan.ryan@email.com

Expected output:

First_name	Last_name
susan	ryan

select
  substr('susan.ryan@email.com',1,(INSTR('susan.ryan@email.com','.')-1)) first_name,
  substr('susan.ryan@email.com',(INSTR('susan.ryan@email.com','.')+1),(INSTR('susan.ryan@email.com','@'))) last_name
from dual;

But i'm getting result as

first_name	Last_name
susan	ryan@email.

Answer 1

You have

substr(email, instr(email, '.') + 1, instr(email, '@')) as last_name

But the second parameter is not the end position, but the requested length, so you must subtract the position of the dot:

substr(email, instr(email, '.') + 1, instr(email, '@') - instr(email, '.') - 1) as last_name

That's easier with REGEXP_SUBSTR by the way:

regexp_substr(email, '[[:alpha:]]+', 1, 1) as first_name,
regexp_substr(email, '[[:alpha:]]+', 1, 2) as last_name

We are looking for substrings that only consist of letters in the e-mail here. For first_name we are taking the first such string, for last_name the second one. This relies of course on all e-mails in your table equally consisting of firstname.lastname@domain.

Here is the docs on REGEXP_SUBSTR : https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/REGEXP_SUBSTR.html#GUID-2903904D-455F-4839-A8B2-1731EF4BD099

Answer 2

Here are some examples of how to do this. First remove the domain using SUBSTR (column "domain") or REGEXP (column "domain_regexp"), then split the portion before the domain (column "no_domain") using REGEXP_SUBSTR :

WITH samples AS
(
  SELECT '-susan.ryan@email.com' as str FROM DUAL UNION
  SELECT 'roger@email.com' as str FROM DUAL
)
SELECT 
str as email,
REGEXP_SUBSTR(str,'@.+$') AS domain_regexp,
SUBSTR(str, INSTR(str,'@')) as domain,
SUBSTR(str, 1, INSTR(str,'@') - 1) as no_domain,
REGEXP_SUBSTR(SUBSTR(str, 1, INSTR(str,'@') - 1),'[^.]+',1,1) AS first_name,
REGEXP_SUBSTR(SUBSTR(str, 1, INSTR(str,'@') - 1),'[^.]+',1,2) AS last_name
from samples;

EMAIL                 DOMAIN_REGEXP         DOMAIN                NO_DOMAIN             FIRST_NAME            LAST_NAME            
--------------------- --------------------- --------------------- --------------------- --------------------- ---------------------
-susan.ryan@email.com @email.com            @email.com            -susan.ryan           -susan                ryan                 
roger@email.com       @email.com            @email.com            roger                 roger