from the_rows_you_want w
left join the_rows_you_dont d
on w.the_condition = d.to_exclude_rows
where d.use_of_not_exists is null;
Personally I prefer to write these queries as not exists as I find them a bit easier
understand. In some cases an outer join with an is null predicate can perform better
as the optimizer can use different join methods (e.g.
where cost > 'more than you budgeted for';
An unindexed merge join of million row tables
While these can both last a lifetime, only one is supposed to! ;)
select posts from sqlfail
dbms_comparison package isn’t deployed when you provision a pluggable databases (PDBs) in Oracle 12c. It appears to be a simple admission. At least, it let me manually compiled the
dbms_comparison package with this syntax:
Somebody wants help provisioning a pluggable database (PDB). While it’s a new concept in the Oracle 12c database, I can sympathize with their plight. It wasn’t clear to me when first working with it, and I couldn’t seem to find a quick tutorial on the web. While it’s in the new Oracle 12c PL/SQL Programming Book, that won’t be out until January 2014.
Here are the steps that work on both Windows, Linux, or Windows:
where sysdate = to_date(sysdate);
no rows selected
As Tom Kyte often says, implicit conversions = evil. In this case putting a to_date
around a date first converts it to a string, then converts it back to a date.
I have been a habitual user of our dryer for years. Out of the washer, into the dryer! Winter, spring, summer, fall....what's wrong with this picture?
Well, do I really need "natural" gas to dry my clothing?
Picked up a drying rack at Costco last week and put it to work today:
where not exists (
where your_job_depends = on_it_working
or you_may_find_the_job = not_existing
Of course, it's a better strategy to put backups and a recovery plan in place than going
around deleting databases without these.
I don't know about you, but my In box functions as my to-do list. Not my only to-do list, mind you. I still scratch out lists on paper with an ancient technology known as a pen. But my In box plays a critical role in reminding me of upcoming items of interest.
I am not the only one, as I was reminded rather forcefully this week.
The PL/SQL Challenge reminds players (who have asked for reminders) about their daily and weekly quizzes. We also send out emails with results, once the quiz has closed.