multi row update in one SQL statment

[Rima]

I have the following two tables :

table a
(commit_id,
capital_market_ id,
chg_lst_date
)

table b
(b_seq_id,
commit_id,
capital_market_ id,
chg_lst_date
)

commid_id is PK in A but not in B. B can have multiple entries per
commit_id.

I want to update all entries in table A - set the capital_market_ id
and chg_lst_date - from the corresponding commit_id entry in table B
with the following two rules :

1. since B can have multiple rows per commit_id I want to pick the one
with the latest txn_time and
2. only update in A if the chg_lst_date of a is less than that of B.

Can I do this in one update statement? or do I have to do a
cursor/loop ?

I originally posted this in oracle.misc but then realized it might be
a non-technical forum - hence this repeat post.

[Nicolas Payre]

Re: multi row update in one SQL statment


"Rima" <parikhrima@yah oo.comwrote in message
news:8a126d63.0 307251222.2b111 47e@posting.goo gle.com...

I have the following two tables :
>
table a
(commit_id,
capital_market_ id,
chg_lst_date
)
>
table b
(b_seq_id,
commit_id,
capital_market_ id,
chg_lst_date
)
>
commid_id is PK in A but not in B. B can have multiple entries per
commit_id.
>
I want to update all entries in table A - set the capital_market_ id
and chg_lst_date - from the corresponding commit_id entry in table B
with the following two rules :
>
1. since B can have multiple rows per commit_id I want to pick the one
with the latest txn_time and
2. only update in A if the chg_lst_date of a is less than that of B.
>
Can I do this in one update statement? or do I have to do a
cursor/loop ?
>
I originally posted this in oracle.misc but then realized it might be
a non-technical forum - hence this repeat post.

update A a
set (a.commit_id, a.capital_marke t_id, a.chg_lst_date) = (
select b.commit_id, b.capital_marke t_id, b.chg_lst_date
from B b
where b.chg_lst_date = ( select max(b1.chg_lst_ date)
from B b1
where b1.commit_id =
b.commit_id
)
)
where a.chg_lst_date < (select max(b2.chg_lst_ date)
from B b2
where b2.commit_id = a.commit_id
)

[Nic]

Re: multi row update in one SQL statment


"Rima" <parikhrima@yah oo.comwrote in message
news:8a126d63.0 307281059.44a09 a8d@posting.goo gle.com...

"Nicolas Payre" <nicpayre[junk]@sympatico.cawr ote in message

news:<TTlUa.887 8$1I5.1134904@n ews20.bellgloba l.com>...

"Rima" <parikhrima@yah oo.comwrote in message
news:8a126d63.0 307251222.2b111 47e@posting.goo gle.com...

I have the following two tables :
>
table a
(commit_id,
capital_market_ id,
chg_lst_date
)
>
table b
(b_seq_id,
commit_id,
capital_market_ id,
chg_lst_date
)
>
commid_id is PK in A but not in B. B can have multiple entries per
commit_id.
>
I want to update all entries in table A - set the capital_market_ id
and chg_lst_date - from the corresponding commit_id entry in table B
with the following two rules :
>
1. since B can have multiple rows per commit_id I want to pick the one
with the latest txn_time and
2. only update in A if the chg_lst_date of a is less than that of B.
>
Can I do this in one update statement? or do I have to do a
cursor/loop ?
>
I originally posted this in oracle.misc but then realized it might be
a non-technical forum - hence this repeat post.

update A a
set (a.commit_id, a.capital_marke t_id, a.chg_lst_date) = (
select b.commit_id, b.capital_marke t_id, b.chg_lst_date
from B b
where b.chg_lst_date = ( select max(b1.chg_lst_ date)
from B b1
where b1.commit_id

=

b.commit_id
)
)
where a.chg_lst_date < (select max(b2.chg_lst_ date)
from B b2
where b2.commit_id = a.commit_id
)

>
Thanks Nicolas.
>

Sorry, ithink a made a mistake the query in my initial post should have
been:

==>See, i added a very important clause ;-)

update A a
set (a.commit_id, a.capital_marke t_id, a.chg_lst_date) = (
select b.commit_id, b.capital_marke t_id, b.chg_lst_date
from B b
where b.chg_lst_date = ( select max(b1.chg_lst_ date)
from B b1
where b1.commit_id
=b.commit_id
)
==> and b.commit_id = a.commit_id
)
where a.chg_lst_date < (select max(b2.chg_lst_ date)
from B b2
where b2.commit_id = a.commit_id
)

I'm a little confused however, according to the docs in the case of
>
update ... set (col,col,col... ) = (subquery)
>
the subquery must return exactly one row.
>
your subquery :
>
select b.commit_id, b.capital_marke t_id, b.chg_lst_date
from B b
where b.chg_lst_date = ( select max(b1.chg_lst_ date)
from B b1
where b1.commit_id = b.commit_id
)
would return multiple rows. How does that work?

it depend on your data!

For exemple, if for a same commit_id you can have multiple row with the
exact same chg_lst_date, then the subquery will return multiple rows.... You
have to know what the data is, or will be. If your not sure, it better to go
with some PL/SQL where you can manage differents case with somme IF/ELSE or
even EXCEPTIONS logic.

The use of constraints will help you ensure what your data is.

Thanks,
Rima.