RE: [HACKERS] ONLY

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От Ansley, Michael
Тема RE: [HACKERS] ONLY
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Msg-id 1BF7C7482189D211B03F00805F8527F748C4F6@S-NATH-EXCH2
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Список pgsql-hackers
>> Been trying to read the SQL3 draft. My best guess is that this
>> is the appropriate section...
>> 
>>              Let T be the table identified by
>>             <ANSI>  <table name>
>>             <ISO >  <table or query name>
>>             contained in a <table specification> TS.
>> 
>> ...
>> 
>>            c) If ONLY is specified, then TS identifies a table fo the
>> rows
>>               that do not have any corresponding row in any 
>> subtable of
>>               T.
>> 
>> I assume this a round-about way of saying that "ONLY" is 
>> used to exclude
>> subtables?
That's not what it sounds like to me.  To me, this sounds like it will only
include those rows that do not have associated rows in sub-tables.  That's
not the same as selecting rows without the associated sub-table rows.  Kind
of a select * from TS where not exists (any rows in sub-tables of TS)

Looking at it again, it does sound very ambiguous, but I would still lean
(semantically, not using common sense) to what I wrote above.  Of course,
common sense would dictate otherwise.

MikeA


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