Oracle 11g Release 2

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create table my_table (
  member_code int, 
  forename varchar(42), 
  surname varchar(42), 
  date_of_birth date);
insert all
 into my_table (member_code,forename,surname,date_of_birth) values (1,'Tom','Hanks',date '1899-12-31')
 into my_table (member_code,forename,surname,date_of_birth) values (2,'Rob','Rob',  date '1999-02-28')
 into my_table (member_code,forename,surname,date_of_birth) values (3,'Al', 'Al',   date '2023-01-01')
select 1 from dual;
3 rows affected

with errors(code,message) as (
   select 1,'Forename less than 3 characters' from dual union all
   select 2,'Date of birth after 31/01/2008' from dual union all
   select 3,'Forename is equal to surname' from dual
)
select a.*, coalesce(e.message,'No Error')
from   my_table a left join errors e on
       (   (e.code=1 and 3>length(a.forename))
        or (e.code=2 and a.date_of_birth>TO_DATE('31/01/2008', 'DD/MM/YYYY'))
        or (e.code=3 and a.forename=a.surname) );


MEMBER_CODE
FORENAME
SURNAME
DATE_OF_BIRTH
COALESCE(E.MESSAGE,'NOERROR')


1
Tom
Hanks
31-DEC-99
No Error

2
Rob
Rob
28-FEB-99
Forename is equal to surname

3
Al
Al
01-JAN-23
Forename less than 3 characters

3
Al
Al
01-JAN-23
Date of birth after 31/01/2008

3
Al
Al
01-JAN-23
Forename is equal to surname

MEMBER_CODE	FORENAME	SURNAME	DATE_OF_BIRTH	COALESCE(E.MESSAGE,'NOERROR')
1	Tom	Hanks	31-DEC-99	No Error
2	Rob	Rob	28-FEB-99	Forename is equal to surname
3	Al	Al	01-JAN-23	Forename less than 3 characters
3	Al	Al	01-JAN-23	Date of birth after 31/01/2008
3	Al	Al	01-JAN-23	Forename is equal to surname