On Thu, 30 Nov 2006, Bernhard Graf wrote:
Matt S Trout wrote:
{ -or => [ { 'chunks.id => undef' }, { 'chunks_2.id' => undef }, {
'chunks.id' => \'!= chunks2.id' } ] }
i.e.
WHERE (chunks.id IS NULL OR chunks_2.id IS NULL OR chunks.id !=
chunks2.id)
It's not amazingly elegant, which is why the JOIN ON syntax is
No. Does not work.
generally preferred, but by and large you can move stuff in and ON
clause into the WHERE clause or vice versa just fine - a LEFT JOIN is
pretty much just a JOIN against all values of that table *plus* a row
consisting entirely of NULLs.
Yeah. And I need the NULLs:
Your query only finds multi-part emails, because only for those
"chunks.id!=chunks_2.id" is true if this is in the WHERE part.
"chunks.id IS NULL OR chunks_2.id IS NULL" in the WHERE part is useless,
because they will never be NULL without "chunks.id!=chunks_2.id" in the
LEFT JOIN.
This is why I hate it when people tell me something "must be"
different to my suggestions without justification - if you don't
explain *why* you think that, I can't tell you the bit you're missing
:)
I'm still not convinced. ;-P
I'm attempting to follow this, and I'm still not convinced.. Can you toss
out an example with actual data, show what rows your query produces, and
what Matt's gets? I also think its possible without better JOIN conds..
(That's not to say I don't want them, I do.. but they do need careful
attention, and many tests ;)
Jess
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