如何仅从联接表中获取平均值

Question

I have the following query:

with D1 as (
        select v06.ID
            ,AVG(TD.A) as A_avg
            ,AVG(TD.B) as B_avg
        from v06
        inner join v07 TD
            on v06.ID= TD.ID
            and v06.timestamp= TD.timestamp
        where v06.X is not NULL
        group by v06.ID
)
select * from D1

Now I'm grouping by v06.ID. However, what I want is to keep all fields of v06 while only adding two averaged values from table TD. So I tried:

with D1 as (
        select v06.*
            ,AVG(TD.A) as A_avg
            ,AVG(TD.B) as B_avg
        from v06
        inner join v07 TD
            on v06.ID= TD.ID
            and v06.timestamp= TD.timestamp
        where v06.X is not NULL
        group by v06.*
)
select * from D1

But that gives me the 'illegal symbol *' on the select statement. Does anyone know how to achieve this?

Answer 1

As one of the comment mention, you can't have a column in the select that isn't in the GROUP BY clause or used in a aggregate function.

Try this:

with D1 as (
        select v06.ID
            ,AVG(TD.A) as A_avg
            ,AVG(TD.B) as B_avg
        from v06
        inner join P.B90T75 TD
            on v06.ID= TD.ID
            and v06.timestamp= TD.timestamp
        where v06.X is not NULL
        group by v06.ID
)
select d2.*, d1.a_avg, d1.b_avg 
from D1 
     join v06 D2 
       on d1.id = d2.id

Answer 2

Or, if available/supported [unknown if, per no mention of platform or release of DB2 in the OP, nor even a platform-specific DB2 tag included], perhaps the following query. Note: remove or adjust the DEC casting scalar as appropriate; I just chose a small value to get a better report size with my sample data because there was no DDL with sample data nor expected result offered in the OP against which to test:

select a.*                                                 
     , dec( avg(a) over(partition by a.id ) , 11 ) as avg_a
     , dec( avg(b) over(partition by a.id ) , 11 ) as avg_b
from v06 as a                                              
join v07 as b                                           
  on a.id = b.id                                           
 and a.timestamp = b.timestamp                             
where x is not null                                        
order by id