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Thread: is it possible to get the number of rows of a table?

is it possible to get the number of rows of a table?

From
Frederick Klauschen
Date:
I would like to compare the number of rows
of one table and of another and use it in
a  query like this:
SELECT * FROM xxxx
WHERE   "number of rows of table xxxx"                 EQUALS                  "number of rows of table yyyy"
i.e. I only want get a query result if the tables
have the same number of rows.
Is there a function or a way to do this ?

Thanks,
Frederick


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Re: is it possible to get the number of rows of a table?

From
"Wei Weng"
Date:
This should be really easy to implement in a function yourself. And I don't
think there is already something similar in pgsql.

==========
Wei Weng
Network Software Engineer
KenCast Inc.



> -----Original Message-----
> From: pgsql-sql-owner@postgresql.org
> [mailto:pgsql-sql-owner@postgresql.org]On Behalf Of Frederick Klauschen
> Sent: Wednesday, September 26, 2001 11:15 AM
> To: pgsql-sql@postgresql.org
> Subject: [SQL] is it possible to get the number of rows of a table?
>
>
> I would like to compare the number of rows
> of one table and of another and use it in
> a  query like this:
> SELECT * FROM xxxx
> WHERE   "number of rows of table xxxx"
>                   EQUALS
>                    "number of rows of table yyyy"
> i.e. I only want get a query result if the tables
> have the same number of rows.
> Is there a function or a way to do this ?
>
> Thanks,
> Frederick
>
>
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Re: is it possible to get the number of rows of a table?

From
Haller Christoph
Date:
> 
> I would like to compare the number of rows
> of one table and of another and use it in
> a  query like this:
> SELECT * FROM xxxx
> WHERE   "number of rows of table xxxx"
>                   EQUALS
>                    "number of rows of table yyyy"
> i.e. I only want get a query result if the tables
> have the same number of rows.
> Is there a function or a way to do this ?
> 
> Thanks,
> Frederick
> 
Basically, the way to find out about the number of rows 
of a table is "select count(*) from t1"
But the select statement above looks odd to me 
(no offence intended). 
To receive a selection of certain rows of a table 
you have to reference at least one column of that 
table in the where clause like in 
"select * from table1 t1 where t1.c1 = (select count(*) from t2)" 
I hope this helps at least a bit. 
Regards, Christoph