> -----Original Message----- > From: rverghese [mailto:ri...@hotmail.com] > Sent: Tuesday, March 06, 2012 4:01 PM > To: pgsql-sql@postgresql.org > Subject: map row in one table with random row in another table > > Hi, I am trying to map every row in one table with a random row in > another. > So for e.g. , for each network in 1 table I am trying to map random > segments from the other table. I have this sql below, but it always > applies the same random segment that it picks to all the rows for the > network. I want each row to have a random segment value. I'm just using > the generate_series function to generate id's as an e.g. > Any suggestions? > > My Query > select id, seg_list from (select generate_series(1,10) as id) as X, > (select segment from segments order by random() limit 1 ) as Y > > I get > > 1;'cob0002' > 2;'cob0002' > 3;'cob0002' > 4;'cob0002' > 5;'cob0002' > 6;'cob0002' > 7;'cob0002' > 8;'cob0002' > 9;'cob0002' > 10;'cob0002' > > What I want is > > 1;'cob0002' > 2;'cob0008' > 3;'cob0006' > 4;'cob0004' > 5;'cob0002' > 6;'cob0007' > 7;'cob0003' > 8;'cob0004' > 9;'cob0009' > 10;'cob0001' >
Try this: Select distinct on (id) id, segment From (select generate_series(1,10) as id) as X, (select segment from segments) as Y Order by id, random(); Depending on the size of your tables, performance could become an issue. Regards, Igor Neyman -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql