Re: Postgres 7.3.5 and count('x') - Mailing list pgsql-hackers

From Peter Eisentraut
Subject Re: Postgres 7.3.5 and count('x')
Date
Msg-id 200312061746.37190.peter_e@gmx.net
Whole thread Raw
In response to Re: Postgres 7.3.5 and count('x')  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Postgres 7.3.5 and count('x')
Re: Postgres 7.3.5 and count('x')
List pgsql-hackers
Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > What is COUNT('x') supposed to return?  1?  Is that legal SQL?
>
> Why not?

Because there is nothing to count.

In general,

SELECT count(expr) FROM table1;

counts the number of rows in table1 where expr evaluates to not null.  
If table1 is not specified, that rule no longer holds.  At best you 
could assume that table1 is empty and return 0.  But a result of 1 I 
cannot see justified.



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