Working with comma seprated string in column

Question

hi,
RDBMS:Oracle 10gR2
I have a table with following structure
Table : t1
id int
emails varchar2 (200)
newEmail varchar2 (150)
Sample data is as following
id   emails                                                                                      newEmail
1    [email protected],[email protected],[email protected]      null
2
[email protected],[email protected],[email protected]            null
I can use following query to extract data from comma separation to row.
select id,regexp_substr(emails, '[^,]+', 1, rownum) Emails
  from t1
  connect by level <= length(regexp_replace(emails, '[^,]+')) + 1
Now I have to perform 2 operations
1- find /count email ids per id, to estimate how many ids has single and how much  have multiple in emails.I have tried following but  it just remain in execution
with Email as
select id,regexp_substr(emails, '[^,]+', 1, rownum) Emails
  from t1
  connect by level <= length(regexp_replace(emails, '[^,]+')) + 1
select id,emails from email
group by id,emails
having count (id)>1;
2- I want to write update newEmail field from  first value in Emails in table t1 and remove updated value from emails field of table. so If emails has 5 email addresses (1,2,3,4,5) in it , after update it will have 4.I a not sure hoow to do that ?
thanks

Answer 1

You need to fix your data model.
Storing multiple values in a single value column is bad database design and breaches the rules of normalization.
SQL> ed
Wrote file afiedt.buf
  1  with t as (select 1 as id, '[email protected],[email protected],[email protected]' as stupid_string from dual union all
  2             select 2, '[email protected],[email protected],email6.domain.com,[email protected]' from dual)
  3  -- ----------------------------------------------------
  4  -- END OF TEST DATA - USE QUERY BELOW AGAINST OWN TABLE
  5  -- ----------------------------------------------------
  6  select id
  7        ,level as email_id
  8        ,regexp_substr(stupid_string,'[^,]+',1,level) as email
  9  from   t
10  connect by id = prior id
11         and level <= regexp_count(stupid_string,',')+1
12         and prior sys_guid() is not null
13* order by 1,2
SQL> /
        ID   EMAIL_ID EMAIL
         1          1 [email protected]
         1          2 [email protected]
         1          3 [email protected]
         2          1 [email protected]
         2          2 [email protected]
         2          3 email6.domain.com
         2          4 [email protected]
7 rows selected.