Replacing Email Domains

Question

I\'m trying to change the inputted domain name to a new domain name, for example, \"hotmail.com\" becomes \"outlook.com\". I believe I\'m on the right track, just my substring i

Answer 1

Code you wrote doesn't make much sense; too much fetching which won't work (two columns into a single variable?).

Here's an example: a test table:

SQL> create table test (email varchar2(30));

Table created.

SQL> insert into test
  2    select 'lf@hotmail.com' from dual union all
  3    select 'bigfoot@net.hr' from dual union all
  4    select 'stack@gmail.com' from dual union all
  5    select 'overflow@gmail.com' from dual;

4 rows created.

How to split domain part from it (2nd column of the following SELECT) and update e-mail addresses to a new domain (3rd column):

SQL> select email,
  2    substr(email, instr(email, '@') + 1) domain,
  3    replace(email,
  4            substr(email, instr(email, '@') + 1),
  5            'new_domain.com'
  6           ) result
  7  from test;

EMAIL                     DOMAIN          RESULT
------------------------- --------------- -------------------------
lf@hotmail.com            hotmail.com     lf@new_domain.com
bigfoot@net.hr            net.hr          bigfoot@new_domain.com
stack@gmail.com           gmail.com       stack@new_domain.com
overflow@gmail.com        gmail.com       overflow@new_domain.com

SQL>

Let's update only Gmail e-mail addresses to a new domain:

SQL> update test set
  2    email = replace(email,
  3                    substr(email, instr(email, '@') + 1),
  4                    'new_domain.com'
  5                   )
  6  where substr(email, instr(email, '@') + 1) = 'gmail.com';

2 rows updated.

SQL> select * From test;

EMAIL
-------------------------
lf@hotmail.com
bigfoot@net.hr
stack@new_domain.com
overflow@new_domain.com

SQL>

If you want to convert it to a procedure, no problem:

SQL> rollback;

Rollback complete.

SQL> create or replace procedure p_change_domain
  2    (par_old_domain in varchar2,
  3     par_new_domain in varchar2)
  4  is
  5  begin
  6    update test set
  7      email = replace(email,
  8                      substr(email, instr(email, '@') + 1),
  9                      par_new_domain
 10                     )
 11    where substr(email, instr(email, '@') + 1) = par_old_domain;
 12  end;
 13  /

Procedure created.

SQL> exec p_change_domain('gmail.com', 'new_domain_2.com');

PL/SQL procedure successfully completed.

SQL> select * From test;

EMAIL
-------------------------
lf@hotmail.com
bigfoot@net.hr
stack@new_domain_2.com
overflow@new_domain_2.com

SQL>

If you desperately want to use cursors (I don't know why would you want to do that; it'll be probably the most inefficient option), here you go:

SQL> rollback;

Rollback complete.

SQL> create or replace procedure p_change_domain
  2    (par_old_domain in varchar2,
  3     par_new_domain in varchar2)
  4  is
  5  begin
  6    for cur_r in (select email from test
  7                  where substr(email, instr(email, '@') + 1) = par_old_domain
  8                 )
  9    loop
 10      update test set
 11        email = replace(email,
 12                        substr(email, instr(email, '@') + 1),
 13                        par_new_domain
 14                       )
 15        where email = cur_r.email;
 16    end loop;
 17  end;
 18  /

Procedure created.

SQL> exec p_change_domain('gmail.com', 'new_domain_3.com');

PL/SQL procedure successfully completed.

SQL> select * From test;

EMAIL
-------------------------
lf@hotmail.com
bigfoot@net.hr
stack@new_domain_3.com
overflow@new_domain_3.com

SQL>

Cursor FOR loop is easier to maintain than your attempt (creating a cursor and a cursor variable, opening the cursor, fetching from it, taking care about exiting the loop, closing the cursor).

But, if you can't live without it, here you go:

SQL> rollback;

Rollback complete.

SQL> create or replace procedure p_change_domain
  2    (par_old_domain in varchar2,
  3     par_new_domain in varchar2)
  4  is
  5    cursor c1 is
  6      select email from test
  7      where substr(email, instr(email, '@') + 1) = par_old_domain;
  8    c1r c1%rowtype;
  9  begin
 10    open c1;
 11    loop
 12      fetch c1 into c1r;
 13      exit when c1%notfound;
 14
 15      update test set
 16        email = replace(email,
 17                        substr(email, instr(email, '@') + 1),
 18                        par_new_domain
 19                       )
 20        where email = c1r.email;
 21    end loop;
 22    close c1;
 23  end;
 24  /

Procedure created.

SQL> exec p_change_domain('gmail.com', 'new_domain_4.com');

PL/SQL procedure successfully completed.

SQL> select * From test;

EMAIL
-------------------------
lf@hotmail.com
bigfoot@net.hr
stack@new_domain_4.com
overflow@new_domain_4.com

SQL>

My suggestion? Use pure SQL, if possible. Or the first PL/SQL procedure. Don't use cursors for this purpose.