On 2/2/2011 04:23, Hal Vaughan wrote:
I'm using this query in a Perl program:
SELECT Distinct x.Search FROM $source.Searches AS x LEFT JOIN searching.Status
AS s
ON x.Search=s.Search AND s.Source='$source' WHERE x.RedoTime'$now' AND
s.Search IS NULL
This program runs other programs that do internet searches. I have different sources
(stored in $source, of course), and source has it's own DB with a table,
Searches. Each row of searches describes a different search that can be done
and each search has a name, which is stored in the Searches column (within the Searches
table, so, yes, I use that name for a table and a column).
When a search is being executed, an entry is placed in searching.Status, with
one row in that table showing the status of the search.
So if I have a source named alpha and searches named one and two and the system is executing the search
one, not only is there a row in alpha.Searches describing one in depth, but there is a row in searching.Status
describing the progress with one.
When each search is done, the RedoTime is set so it's easy to see when it needs
to be executed again.
What I want to do is get a list of searches in the Searches table (within the
source's DB) that are NOT listed in Status and where the RedoTime is before
$now (the current time).
From what I've read, the query above should do it, but I have this nagging
feeling I've done something wrong.
Will that query pick up all rows in $source.Searches that have a RedoTime
before $now that are NOT also listed in searching.Status?
Thanks for any help on this!
Maybe today isn't my day. I can't distinguish between what you are
looking for and what you do not want to find.
WANTED:
a list of searches in the Searches table (within the source's DB) that
are NOT listed in Status and where the RedoTime is before $now (the
current time).
NOT WANTED:
rows in $source.Searches that have a RedoTime before $now that are NOT
also listed in searching.Status
I can't seem to spot the difference. Maybe if you phrased it differently
or provided two or three sample rows for each table I could understand
your distinction?
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