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 > -- Simon Litwan simon.litwan@xxxxxxxxx Wyona Inc. - Open Source Content Management - Apache Lenya http://www.wyona.com http://lenya.apache.org
