Re: Create loop in postgresql

Hello Robert,

I just gave an example and this also can be optimized . but let me first clarify one thing here.
 
since you have the same behaviour for all values , there is no need to use case in the first place. So just drop it.

I think below would be the correct syntax

select name,ges_kw_zgb, (SELECT round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2)) FROM energie.tennet_auswertung_2010;

Regards

________________________________
From: Robert Buckley <robertdbuckley(at)yahoo(dot)com>
To: salah jubeh <s_jubeh(at)yahoo(dot)com>; "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Sent: Monday, September 3, 2012 6:06 PM
Subject: Re: [GENERAL] Create loop in postgresql

this give an error.

select name,ges_kw_zgb, SELECT round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2);

ERROR:  syntax error at or near "SELECT"
LINE 2: select name,ges_kw_zgb, SELECT round(100 * (ges_kw_zgb / (se...

________________________________
Von: salah jubeh <s_jubeh(at)yahoo(dot)com>
An: Robert Buckley <robertdbuckley(at)yahoo(dot)com>; "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Gesendet: 17:45 Montag, 3.September 2012
Betreff: Re: [GENERAL] Create loop in postgresql

I am wondering why do not you write it like this

select name,ges_kw_zgb, select round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2) ......

Regards

________________________________
From: Robert Buckley <robertdbuckley(at)yahoo(dot)com>
To: "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Sent: Monday, September 3, 2012 5:30 PM
Subject: [GENERAL] Create loop in postgresql

Hi,

I am trying to loop through the records in a table and update a column. I can do this with a case statement but I would like to simplify this to a simple loop statement. I can´t seem to work out how to do it though.

Here is the case statement.

select name,ges_kw_zgb,
case
When name='Bad Harzburg' then (select round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2))
When name='Braunlage' then (select round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2))
When name='Braunschweig' then (select round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2))
When name='Büddenstedt' then (select round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2))

End as z

from energie.tennet_auswertung_2010
;

 Instead of having to write the name variable in the function, I would just like to iterate through each record and execute the select round(100 * (ges_kw_zgb / (select sum(ges_kw_zgb) From energie.tennet_auswertung_2010)),2) command. 

If anyone can help I´d me grateful,

cheers,

Rob