SQL Select and From Functions

Question

Can sql aggregate functions be added to an interface select clause and from clause.
I want to have a datasource where one of the columns is an aggregate such as a count, which would need the ability to indicate a from clause function group by, or having by. In the Designer Diagram tab for the interface, it seems you can only apply sql functions to where clause joins or filters.
I want to have a query such as follows as my datasource
select columnA, count(*) as thecount
from table x
group by columnA
order by thecount asc
and ultimately
select columnA, thecount
from (select columnA, count(*) as thecount
from table x
group by columnA
order by thecount asc)
where rownum <1001
Can this be done in the ODI Designer, without creating a physical custom view on the database?

Answer 1

Hi lpantuso,
Aggregate functions are added by ODI automatically. In this case you would want mappings like this:
TARGET_COL_1: columnA
TARGET_COL_2: count(*)
ODI will generate something like this:
select     
   columnA,
   count(*)
from     MY_TABLE MY_TABLE
where     
     (1=1)
Group By MY_TABLE.columnA
The subselect, however, isn't handled out of the box. In general ODI isn't quite as friendly with ordering clauses since order by is not relational. (Sets aren't ordered.) To get only the first 1000 columnA values, you'll probably need to create a view or break it into 2 separate interfaces.
Regards,
Matt