Markus and Gábriel: Thank you very much for the help. Yes, the table is redundant. What I am trying to do is using pgdijstra module from postGIS which is on the top of postgreSQL. And the module asks for entire network is directional or non-directional. But my network part is directional and other part is non-directional. I made it is directional by duplicate all non-directional edges into 2 directional edges and it is where redundant come from. And the module only accept data from one table, so I have to keep all data in one table.
Thanks again. Fay -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gábriel Ákos Sent: Tuesday, March 28, 2006 12:34 PM To: pgsql-sql@postgresql.org Subject: Re: [SQL] Update question Markus Schaber wrote: > Hi, Fay, > > Fay Du wrote: >> Table cost >> >> Id edge_id cost >> 1 30 101.4 >> 2 30 null >> 3 40 500.2 >> 4 40 null >> 5 45 300.7 >> 6 45 null > >> I want to set cost value with same edge_id by same value. The existing >> values are calculated by calling a function (calculate edge length). I >> can calculate the value by same function, but the function was slow. I >> wander if I can use update statement to set the second value with same >> edge_id. Thanks in advance for your help. > > It should go like: > > UPDATE cost SET edge_id = (SELECT cost FROM cost innr WHERE innr.edge_id > = edge_id AND innr.cost is not null) WHERE cost is null; > > HTH, > Marku > This is ok, but this is redundant, i guess. you should put edge_id and cost into another table and use join to retrieve cost for each id. put a key on edge_id, most likely a primary (unique) key. -- Üdvözlettel, Gábriel Ákos -=E-Mail :[EMAIL PROTECTED]|Web: http://www.i-logic.hu=- -=Tel/fax:+3612367353 |Mobil:+36209278894 =- ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
