On Mit, 2006-06-21 at 00:09 +0200, simon wrote: > On Die, 2006-06-20 at 15:34 -0500, Bruno Wolff III wrote: > > On Tue, Jun 20, 2006 at 12:06:24 +0200, > > simon <simon.litwan@xxxxxxxxx> wrote: > > > hi all > > > > > > i'm using postgres 7.3 > > > > > > my problem is i want to build a helper table: > > > > > > UPDATE studienmodul_summary > > > SET kategorie = (SELECT kategorie_bezeichnung > > > > > > if the SELECT gives back just one result row, everthing is easy. my > > > problem is, there is sometimes more than one result row. > > > > > > is there a way to concatenate all result rows and insert them in one > > > field? > > > > Yes. You can have the subselect call a custom aggregate function that does > > this for you. Sample code for doing this has been posted on the list > > multiple times and you should be able to find it in the archives. > > thanks for this hint i didn't konw about the custom aggregate function. > i found comma_aggregate(text,text) amd similar examples. > unfortunatly i didn't found something like comma_aggregate(SELECT...). > > is it possible to write an aggregate function that takes the result rows > of any number and makes a long string out of it? > > it would be great if someone would have done something before and is > willing to share. > but hints where to find docu and/or howtos about writting > customaggregate functions are also very welcom. > > simon > > or in other words, i just would like to know how to rewrite SET kategorie = array_to_string ((SELECT ARRAY (SELECT kategorie_bezeichnung so it works in psql7.3 as well. simon -- Simon Litwan simon.litwan@xxxxxxxxx Wyona Inc. - Open Source Content Management - Apache Lenya http://www.wyona.com http://lenya.apache.org
