Oracle aggregate for joining strings with comma, and about writing custom aggregates

Question

How can i create a function on Oracle like sum, min, max?

it will run on result set.

Select join(',', Name), sum(total) From Account Group By IdCity

Answer 1

Here is a link to the documentation that describes how you can create your own aggregate functions: http://download.oracle.com/docs/cd/E11882_01/appdev.112/e10765/aggr_functions.htm

Regards,
Rob.

Answer 2

Use wmsys.wm_concat if Oracle version is 10 or more.

You can also do a lookup on creating aggregate functions in Oracle.

Note that SQLite has the group_concat builtin aggregate if maybe you were interested in it.

Answer 3

Check out the listagg function. It's a solution to your problem (although it doesn't describe how to build your own aggregate function).