From: Steve Crawford <scrawford@pinpointresearch.com>
Organization: Pinpoint Research
To: Wei Weng <wweng@kencast.com>,
	"'pgsql-sql@postgresql.org'" <pgsql-sql@postgresql.org>
Subject: Re: Cast NULL into Timestamp?
Date: Fri, 10 Dec 2004 16:10:16 -0800
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On Friday 10 December 2004 11:24 am, Wei Weng wrote:
> I have a table
>
> create table temp
> (
> 	tempdate	timestamp,
> 	tempname	varchar(10)
> );
>
> And I tried to insert the following:
>
> insert into table temp (tempname, tempdate)
> select distinct 'tempname', null from some_other_relevant_table;
>
> And I got an error that says "column "tempdate" is of type
> timestamp ... but expression is of type text... will need to
> rewrite or cast the expression".
>
> I really need the distinct. Is there anyway to cast this NULL into
> a timestamp or any other workarounds?

How about:
insert into table temp (tempname)
select distinct 'tempname' from some_other_relevant_table;

Unless there's something you have left out in describing your setup 
this will leave the tempdate column null.

Cheers,
Steve