From: | Rajesh Kumar Mallah <mallah(dot)rajesh(at)gmail(dot)com> |
---|---|
To: | Bill Moran <wmoran(at)potentialtech(dot)com> |
Cc: | Postgres General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: select count(*) |
Date: | 2011-03-09 19:09:43 |
Message-ID: | AANLkTinKwwnLwv+wwESb9byz8DE70KPjw3xLiRJ0E+4A@mail.gmail.com |
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Thread: | |
Lists: | pgsql-general |
i "discovered" it as a result of typo :)
we usually select expressions without tables
eg select 1+2 ; etc and the results are as expected,
somehow i failed to stretch the analogy to count(*)
which is mostly used over tables or table expression.
thanks anyways.
regds
mallah.
On Wed, Mar 9, 2011 at 11:20 PM, Bill Moran <wmoran(at)potentialtech(dot)com>wrote:
> In response to Rajesh Kumar Mallah <mallah(dot)rajesh(at)gmail(dot)com>:
>
> > Dear List ,
> >
> > if we simply do select count(*) and not specify any table then it gives 1
> > eg:
> >
> > bric=# SELECT count(*) from job ;
> > count
> > -------
> > 2380
> > (1 row)
> >
> > bric=# SELECT count(*) job ;
> > job
> > -----
> > 1
> > (1 row)
> >
> >
> >
> > bric=# SELECT count(*) ;
> > count
> > -------
> > 1
> > (1 row)
> >
> >
> >
> > bric=# SELECT count(*) job_non_exist ;
> > job_non_exist
> > ---------------
> > 1
> > (1 row)
> >
> > bric=# SELECT count(*) jo1b ;
> > jo1b
> > ------
> > 1
> > (1 row)
> >
> > bric=# SELECT count(*) none ;
> > ERROR: syntax error at or near "none"
> > LINE 1: SELECT count(*) none ;
> >
> >
> > I fail to see any progression ?
>
> When you don't specify a FROM clause, you get 1 because it's
> returning 1 row. No matter what you alias the result to, it's not going
> to change the result, unless of course you try to alias it to an SQL
> reserved word, such as "none", without quoting it. Of course, if you
> include the optional AS, it probably makes more sense what's going on:
>
> SELECT count(*) AS jolb;
> SELECT count(*) AS none;
> SELECT count(*) AS "none";
>
> --
> Bill Moran
> http://www.potentialtech.com
> http://people.collaborativefusion.com/~wmoran/
>
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