My PHP sucks big time please help!
I have 2 tables A and B which both contain column called TID
How can I fetch TIDs from column A that are not in the column B?
(2015-06-11, 02:57 PM)marcus123 Wrote: [ -> ]2 tables A and B
[...]
column A [...] column B?
Trying to treat tables as columns may be your problem...
Assuming you meant 'table' throughout, there may be a few ways to write the SQL. Perhaps the most obvious is a correlated query:
SELECT tid FROM A WHERE tid NOT IN (SELECT tid FROM B)
If the tid columns are unique, a join could also work:
SELECT A.tid FROM A
LEFT JOIN B ON A.tid=B.tid
WHERE B.tid IS NULL
Thanks buddy for reply.
Here is what I mean. I have a table called
Ads which has a column called
tid right. This TID column stores tids that correspond to forum real TIDs
I would like to fetch all
thread tids and then all
ads tids compare them and then output
Thread tids that are not in the
Ads tid column.
$query = $db->query("
SELECT t.tid
FROM ".TABLE_PREFIX."threads t
WHERE t.tid NOT IN (how to fetch ads tid from here)
");
When I fetch tids they all show like one long number. How to put a comma in the middle to use it in
NOT IN expression
$query2 = $db->query("
SELECT t.tid
FROM ".TABLE_PREFIX."threads t
WHERE t.tid NOT IN (SELECT a.tid
FROM ".TABLE_PREFIX."ads a)
");
Is this OK to use? Looks ugly to me!
Well it looks kind of beautiful to me.
I'm not sure what you mean by "ugly".
Be aware that if you have a lot of threads, that query could be expensive (you'll need to test that), if it's run often.
I mean that looks like it's gonna generate a ton of queries! I have like 4000+ threads + as many ads.
How to fetch thread tids separately to only generate one query and then use that value or array in this other query?
Is there a way to call $tids from custom page?
How exactly can one query with a subquery generate ton of queries?
D666 do you think it will only generate one query? Since this is a custom page that I will only use one time I don't think it will put too much stress on the script right?
(2015-06-14, 02:40 PM)marcus123 Wrote: [ -> ]D666 do you think it will only generate one query? Since this is a custom page that I will only use one time I don't think it will put too much stress on the script right?
It doesn't depend on the number of threads. The number of queries depends upon how many times $db->query(); method is executed.
So if you execute it once, only 1 query will be generated.
Depending on the query it may be expensive to run it.
But since you are only going to run it once (apparently) just do it and be done with it.