Question

How to aggregate string( concatenate) with Oracle 10g SQL?

Answer 1

You could try the collect function:

http://www.oracle-developer.net/display.php?id=306

Some other tricks are here:

http://www.oracle-base.com/articles/misc/StringAggregationTechniques.php

…If you actually mean concatenation instead of aggregation then take everyone else’s advice and use the || operator between the two strings:

select 'abc'||'def' from dual;