Re: Question about a query with two count fields
От | George Pavlov |
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Тема | Re: Question about a query with two count fields |
Дата | |
Msg-id | 8C5B026B51B6854CBE88121DBF097A8601216060@ehost010-33.exch010.intermedia.net обсуждение исходный текст |
Ответ на | Re: Question about a query with two count fields (David Fetter <david@fetter.org>) |
Ответы |
Re: Question about a query with two count fields
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Список | pgsql-general |
> From: David Fetter [mailto:david@fetter.org] > On Tue, Sep 11, 2007 at 08:55:53AM -0700, George Pavlov wrote: > > sum(case when z!=0 then 1 end) as good, > > This case statement returns true when z factorial is zero, so I'd > recommend the SQL standard <> or IS NOT DISTINCT FROM instead. and what would be that number that has its factorial = 0 ?! (just giving you a hard time this not being a math forum...) thanks dave, you do bring a valid point of there being ambiguity about the ! and that might be worth noting in the manual (http://www.postgresql.org/docs/8.2/interactive/functions-comparison.htm l). however, it seems that our favorite DBMS does the right thing and gives precedence to the != as "not equal", so taking a more realistic example (non-zero factorials): foo=> select 2 != 2; ?column? ---------- f (1 row) foo=> select 2 <> 2; ?column? ---------- f (1 row) foo=> select (2 !)= 2; ?column? ---------- t (1 row) i do hate potential ambiguity... the != was something stuck in my brain from old sybase, i think. i always liked != ("not equals") as more intuitive than <> ("less than, greater than"???), but i will have to change my ways, especially if "the standard" says so.
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