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	<4B7D0704.70301@archonet.com>
From: Amitabh Kant <amitabhkant@gmail.com>
Date: Thu, 18 Feb 2010 15:03:36 +0530
Message-ID: <84b68b3d1002180133x549f2b07p6d40682cd94d1d86@mail.gmail.com>
Subject: Re: Referencing external table in update/insert triggers
To: Richard Huxton <dev@archonet.com>
Cc: pgsql-sql@postgresql.org
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On Thu, Feb 18, 2010 at 2:53 PM, Richard Huxton <dev@archonet.com> wrote:

> On 17/02/10 15:18, Amitabh Kant wrote:
>
>>
>> CREATE OR REPLACE FUNCTION update_data() RETURNS TRIGGER AS $update_data$
>> BEGIN
>>     IF NEW.t1f4>  t2.t2f4
>>         UPDATE t2 set t2f2=NEW.t1f2, t2f3=NEW.t1f3, t2f4=NEW.t1f4 where
>> t2f1=NEW.d1;
>>         RETURN NEW;
>>     END IF;
>> END;
>> $update_data$ LANGUAGE plpgsql;
>>
>
>  I would like to compare the date present in the t2f4 with the new data
>> being
>> updated through the trigger.  Using the if line as listed above returns an
>> error.
>>
>
> You can always do something like:
>  SELECT t2.t2f4 INTO my_variable FROM t2 WHERE ...
>  IF NEW.t1f4 > my_variable
>
> However, for this case you can just do an update with an extended where
> clause:
>  UPDATE t2 ... WHERE t2f1=NEW.d1 AND NEW.t1f4 > t2.t2f4
>
> No need for the IF.
>
> --
>  Richard Huxton
>  Archonet Ltd
>


Thanks Richard.

With regards

Amitabh Kant

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<br><br><div class=3D"gmail_quote">On Thu, Feb 18, 2010 at 2:53 PM, Richard=
 Huxton <span dir=3D"ltr">&lt;<a href=3D"mailto:dev@archonet.com">dev@archo=
net.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D=
"margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padd=
ing-left: 1ex;">

<div class=3D"im">On 17/02/10 15:18, Amitabh Kant wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; borde=
r-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
CREATE OR REPLACE FUNCTION update_data() RETURNS TRIGGER AS $update_data$<b=
r>
BEGIN<br>
 =A0 =A0 IF NEW.t1f4&gt; =A0t2.t2f4<br>
 =A0 =A0 =A0 =A0 UPDATE t2 set t2f2=3DNEW.t1f2, t2f3=3DNEW.t1f3, t2f4=3DNEW=
.t1f4 where<br>
t2f1=3DNEW.d1;<br>
 =A0 =A0 =A0 =A0 RETURN NEW;<br>
 =A0 =A0 END IF;<br>
END;<br>
$update_data$ LANGUAGE plpgsql;<br>
</blockquote>
<br>
</div><div class=3D"im"><blockquote class=3D"gmail_quote" style=3D"margin: =
0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left:=
 1ex;">
I would like to compare the date present in the t2f4 with the new data bein=
g<br>
updated through the trigger. =A0Using the if line as listed above returns a=
n<br>
error.<br>
</blockquote>
<br></div>
You can always do something like:<br>
 =A0SELECT t2.t2f4 INTO my_variable FROM t2 WHERE ...<br>
 =A0IF NEW.t1f4 &gt; my_variable<br>
<br>
However, for this case you can just do an update with an extended where cla=
use:<br>
 =A0UPDATE t2 ... WHERE t2f1=3DNEW.d1 AND NEW.t1f4 &gt; t2.t2f4<br>
<br>
No need for the IF.<br><font color=3D"#888888">
<br>
-- <br>
 =A0Richard Huxton<br>
 =A0Archonet Ltd<br>
</font></blockquote></div><br><br>Thanks Richard. <br><br>With regards<br><=
br>Amitabh Kant<br>

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