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Date: Tue, 15 Jun 1999 14:42:03 +0200
From: =?iso-8859-1?Q?Jos=E9?= Soares <jose@sferacarta.com>
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To: vikrant@chemquick.com
CC: pgsql-sql@postgresql.org
Subject: Re: [SQL] Mail about typecast
References: <3765C5B3.C05DC56D@chemquick.com>
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Vikrant Rathore ha scritto:

> Dear friends,
>
>     I want to run a query :
>
> vikrant=> select date_part('epoch','12 hours'::timespan)::float4;
> It returns a error message
> ERROR:  function dtof(float8) does not exist
>
> But i want to use typecast since the result of this query will be used
> to update a field of type float4.
>
> I have checked the pg_proc system table it has a function dtof with
> float8 as argument i have checked the list of functions also and
> 'dtof(float8)' is shown in that list also.
> can anyone solve this problem. I can solve the problem by using a c
> program but i want to know when the function dtof(float8) is there in
> pg_proc table then why it is not doing a typecasting.
> Thanks in advance for your kind suggestion.
>
> Thanks & regards,
> Vikrant.

Which version of PostgreSQL are you using?
This works for me. (v6.5)

hygea=> \df dtof
result|function|arguments|description
------+--------+---------+------------------------
float4|dtof    |float8   |convert float8 to float4
(1 row)

hygea=> select date_part('epoch','12 hours'::timespan)::float4;
float4
------
 43200
(1 row)

hygea=> select date_part('epoch','12 hours'::timespan);
date_part
---------
    43200
(1 row)

______________________________________________________________
PostgreSQL 6.5.0 on i586-pc-linux-gnu, compiled by gcc 2.7.2.3
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jose'


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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
&nbsp;
<p>Vikrant Rathore ha scritto:
<blockquote TYPE=CITE>Dear friends,
<p>&nbsp;&nbsp;&nbsp; I want to run a query :
<p>vikrant=> select date_part('epoch','12 hours'::timespan)::float4;
<br>It returns a error message
<br>ERROR:&nbsp; function dtof(float8) does not exist
<p>But i want to use typecast since the result of this query will be used
<br>to update a field of type float4.
<p>I have checked the pg_proc system table it has a function dtof with
<br>float8 as argument i have checked the list of functions also and
<br>'dtof(float8)' is shown in that list also.
<br>can anyone solve this problem. I can solve the problem by using a c
<br>program but i want to know when the function dtof(float8) is there
in
<br>pg_proc table then why it is not doing a typecasting.
<br>Thanks in advance for your kind suggestion.
<p>Thanks &amp; regards,
<br><tt>Vikrant.</tt></blockquote>
<tt>Which version of PostgreSQL are you using?</tt>
<br><tt>This works for me. (v6.5)</tt><tt></tt>
<p><tt>hygea=> \df dtof</tt>
<br><tt>result|function|arguments|description</tt>
<br><tt>------+--------+---------+------------------------</tt>
<br><tt>float4|dtof&nbsp;&nbsp;&nbsp; |float8&nbsp;&nbsp; |convert float8
to float4</tt>
<br><tt>(1 row)</tt><tt></tt>
<p><tt>hygea=> select date_part('epoch','12 hours'::timespan)::float4;</tt>
<br><tt>float4</tt>
<br><tt>------</tt>
<br><tt>&nbsp;43200</tt>
<br><tt>(1 row)</tt><tt></tt>
<p><tt>hygea=> select date_part('epoch','12 hours'::timespan);</tt>
<br><tt>date_part</tt>
<br><tt>---------</tt>
<br><tt>&nbsp;&nbsp;&nbsp; 43200</tt>
<br><tt>(1 row)</tt><tt></tt>
<p>______________________________________________________________
<br>PostgreSQL 6.5.0 on i586-pc-linux-gnu, compiled by gcc 2.7.2.3
<br>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
<br>Jose'
<br>&nbsp;</html>

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