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Re: Create loop in postgresql

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And probably the op
would prefer to avoid recalculating the sum once for every row.....

select name,ges_kw_zgb, round(100*ges_kw_zgb/total.totalsum, 2) as z
from energie.tennet_auswertung_2010, (select sum(ges_kw_zgb) totalsum From energie.tennet_auswertung_2010) as total
where ......


Regards
Rainer

On 03.09.2012 17:45, salah jubeh wrote:
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@xxxxxxxxx>
To: "pgsql-general@xxxxxxxxxxxxxx" <pgsql-general@xxxxxxxxxxxxxx>
Sent: Monday, September 3, 2012 5:30 PM
Subject: 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




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