merge statement gives error

[Abhra Kar <abhra.kar@xxxxxxxxx>]

Hi,

       Trying to execute the following statement ---- 

merge into ABC as n using dual on (n.id=123)

when matched update set aaa=222, bbb=333

 when not matched insert (id, aaa) values (NEXTVAL(id),555);

but gives syntax error.What should be the proper syntax[ Parameter values are properly passed based on data type].

Thanks