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Re: does a table always need a PK?

From: Mikito Harakiri <mikharakiri_at_ywho.com>
Date: Tue, 2 Sep 2003 18:23:47 -0700
Message-ID: <Xwb5b.22$1o4.1108@news.oracle.com> 





"Lee Fesperman" <firstsql_at_ix.netcom.com> wrote in message
news:3F553E89.5AD9_at_ix.netcom.com...


 > You might replace count(*) with sum(1), but count(a + b) only counts
tuples where (a+b)


> is not NULL.




The general rule is: "If you have a problem with null, just add a switch
operator":



sum(case when a+b is null then 0 else 1 end)
Received on Tue Sep 02 2003 - 20:23:47 CDT












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