Re: What does LIKE '%%' actually do in a WHERE clause?
- From: Norman Dunbar <oracle@xxxxxxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Fri, 07 Oct 2011 08:52:19 +0100
Morning Grant,
> Maybe I'm mis-interpreting things, but wouldn't LIKE '%' actually be
> semantically equivalent to IS NOT NULL. That is, for something to be LIKE
> "anything", it must therefore be known (or more specifically knowable) in
> order to evaluate its "likeness".
Yes, to all intents and purposes, they are equivalent. I haven't checked
if the CBO considers them to be the same though!
> The %% thing is however, new and interesting to me :)
It had me foxed as well. I'd never seen it until this came up, and I
thought it was a special format of the wildcard - I admit that at first
I thought it was a way of specifying the percent sign - why would they
be looking for a string like '%' came to mind! ;-)
Cheers,
Norm.
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Norman Dunbar
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