表中每个条件更新一条记录

Question

I looked into this thread, and I thought I'd find my answers there, but unfortunately didn't ...

UPDATE statement in Oracle using SQL or PL/SQL to update first duplicate row ONLY

If our customers don't have a default email address selected I need to update that value.

The following statement updates ALL records of that table if the customer does not have a default email yet:

update si_contactemails 
set ISDEFAULT = 'Y'
where entityid in
(select customerid from si_customers where custstatus = 'A' and deleted = 0)
and entityid in (select entityid from si_contactemails group by entityid having MAX(ISDEFAULT) = 'N')

But if a customer happens to have more than one entry in the si_contactemails table I only need the first record for this customer updated, can only have one default.

I tried with the following addition which I found in the article mentioned above, but it only updates the first record for which all conditions are true - how can I update all records for which the conditions are true?

update si_contactemails 
set ISDEFAULT = 'Y'
where entityid in
(select customerid from si_customers where custstatus = 'A' and deleted = 0)
and entityid in (select entityid from si_contactemails group by entityid having MAX(ISDEFAULT) = 'N')
AND rowid = (SELECT min(rowid) 
                 FROM   si_contactemails 
                 WHERE entityid in (select min(entityid) from si_contactemails group by entityid having MAX(ISDEFAULT) = 'N'))

Any input appreciated :-)

Thanks a lot,

Steph

Answer 1

Here's one approach:

UPDATE si_contactemails
   SET isdefault = 'Y'
 WHERE rowid IN
        ( SELECT MIN(rowid)
            FROM si_contactemails
           WHERE entityid IN
                  ( SELECT customerid
                      FROM si_customers
                     WHERE custstatus = 'A'
                       AND deleted = 0
                    MINUS
                    SELECT entityid
                      FROM si_contactemails
                     WHERE isdefault = 'Y'
                  )
           GROUP
              BY entityid
        )
;

It finds exactly one rowid in si_contactemails for each customer that (1) has status A and is not deleted and (2) has no default record in si_contactemails . It then updates every record in that set of rowid s.

(Disclaimer: not tested.)