Re: how does this delete work?
- From: Mark D Powell <Mark.Powell@xxxxxxx>
- Date: Mon, 09 Jul 2007 09:34:18 -0700
On Jul 9, 11:09 am, steph <stepha...@xxxxxxxx> wrote:
Hi,
Recently I came across this delete statement inside a package that I
have to debug:
DELETE FROM
(
SELECT 1
FROM KUNDEN_SOLL ks, KUNDEN k
WHERE ks.ksl_kun_id = k.kun_id
...
)
I must say the syntax is a little uncommon for me. What's the
advantage of doing things that way instead of issuing a plain "delete
from table where ..."?
thanks,
stephan
Stephan, the syntax allows DML, a delete in this case, to be performed
on rows of a key preserved table based on the results of a join
without defining the join view to the database as a permanent view.
Writing the code this way can be more efficient than having to code
the requirements as sub-queries.
See the Applications Developers Guide - Fundamentals, ch 2, Managing
Schema Objects, section Modifying a Join View for limitations of join
views and for information on key preserved tables.
The material in the manual used defined views (create view x) but it
is the same concept in use.
HTH -- Mark D Powell --
.
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