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Re: comparing rows

From: Don Baccus <dhogaza(at)pacifier(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu>, Magnus Hagander <mha(at)sollentuna(dot)net>, Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: comparing rows
Date: 2000-08-03 14:37:17
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Lists: pgsql-hackers
At 10:23 AM 8/3/00 -0400, Tom Lane wrote:
>Don Baccus <dhogaza(at)pacifier(dot)com> writes:
>> If foo = NULL is illegal, doesn't this make it rather difficult to
>> say things like table1.i = table2.i for tables that contain NULLs
>> in column i?
>Thomas is not saying that the *operation* is illegal.  His point is
>purely a syntactic one: SQL92 allows the keyword "NULL" only in certain
>specified contexts, and out on its own as a component of an arithmetic
>expression ain't one of them. 

I misunderstood, didn't check for the use of the literal, just the
semantics of the operations.

>As far as I can see, allowing NULL as a general-purpose literal is a
>perfectly reasonable spec extension that *everybody* does, including us.
>Thomas may be the only person anywhere who is bothered by it ;-)

Thomas, do you have a reference into the standard?

- Don Baccus, Portland OR <dhogaza(at)pacifier(dot)com>
  Nature photos, on-line guides, Pacific Northwest
  Rare Bird Alert Service and other goodies at

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