SQL - updating Oracle 10g database from a complex query - sql

Question

trying to update a single column based on criteria. The rows that need to be updated are returned by the query
SELECT
it.objectid,
it.versionnumber,
it.itemnumber "Item Number",
it.itemtype,
itcovprem.basisofsettlement,
itcovprem.coverage "Coverage"
FROM
itemcoveragesandpremiums itcovprem,
items it,
policies pl
WHERE
pl.objectid = it.parentobjectid AND
pl.policytype in ('H','F') AND
it.objectid = itcovprem.itemobjectid AND
it.itemtype in ('SHOA','SHOB','SHOC','SHOD','SHOK','SHOL') and
it.versionnumber = itcovprem.itemversionnumber AND
((itcovprem.coverage like ('A - Dwg Bldg%')) or
(itcovprem.coverage like ('#42 - Repl Cost Plus%')) or
(itcovprem.coverage like ('#42 - Limited GRC%'))) and
it.effectivedate >= TO_DATE('01-JAN-2006', 'DD-MON-YYYY') and
exists (select * from itemcoveragesandpremiums icp where icp.itemobjectid = it.objectid and icp.itemversionnumber = it.versionnumber and icp.coverage like ('#42%')) and
itcovprem.basisofsettlement not in ('LGRC')
I've tried a few options to convert this to an update query, but no joy.
I get Error - line 3 - SQL command not properly ended when using
update itemcoveragesandpremiums
set basisofsettlement = 'LGRC'
from itemcoveragesandpremiums as itcovprem
inner join items as it
on it.objectid = itcovprem.itemobjectid and it.versionnumber = itcovprem.itemversionnumber
inner join policies as pl
on pl.objectid = it.parentobjectid
where [cut, rest of query was below]
I get Error - line 6 - missing right parenthesis when trying use an inline query
update
(
SELECT
itcovprem.basisofsettlement as OLD
FROM
itemcoveragesandpremiums as itcovprem inner join items as it on it.objectid = itcovprem.itemobjectid and it.versionnumber = itcovprem.itemversionnumber inner join policies AS pl on pl.objectid = it.parentobjectid
WHERE [query snipped]
) t
set t.old = 'LGRC'
Seems that SQL*Plus just wants to stop looking at the update before it gets to the meat of my select query. I'm not sure if I'm formatting it incorrectly or going at it from the wrong direction. Any advice?

Answer 1

In your first attempt, the error at line 3 is because update doesn't support a from or join clause. In your second attempt the immediate error at line 6 is because you're trying to alias a table with as itcovprem; but you can only use as for column aliases, not for table aliases. (The first attempt is trying to do that too, but it isn't getting as far as encountering that problem). But you can't generally update an inline-view with joins anyway, so it would still error with that - something like an ORA-01779.
You would need to do something like:
update itemcoveragesandpremiums
set basisofsettlement = 'LGRC'
where (itemobjectid, itemversionnumber, basisofsettlement, coverage) in (
select it.objectid,
it.versionnumber,
itcovprem.basisofsettlement,
itcovprem.coverage
from ...
)
Assuming that itemobjectid, itemversionnumber, basisofsettlement, coverage identifies a row sufficiently such that you don't risk updating anything you shouldn't. It might be safer to add a rowid to the select and use that for the update instead to avoid ambiguity:
update itemcoveragesandpremiums
set basisofsettlement = 'LGRC'
where rowid in (
select itcovprem.rowid as target_rowid
from ...
)