Question

Sorry for the title, not easy to phrase it correctly.

I have a table A which has a business key (Akey) with possible value range : k1, k2 and k3

AKey ACol2  ACol3
k1   val12  val13
k2   val22  val23
k3   val32  val33

I have a table B which has entries like

BKey1 BKey2 BKey3  AKey Col5  Col6
kk11  kk12  kk13   k1   val15 val16
kk21  kk22  kk23   k3   val25 val26

BKey1, BKey2 and Bkey3 is the business key of table B
Akey is a foreign key to table A

I would like to generate a result set with table B joined with table A (on AKey) but include “empty” lines for non referenced key from table A (and this for each key of table B). In the example I would like to have :

BKey1 BKey2 BKey3  AKey Col5  Col6   ACol2 ACol3
kk11  kk12  kk13   k1   val15 val16  val12 val13
kk21  kk22  kk23   k3   val25 val26  val32 val33
kk11  kk12  kk13   k2   def   def    val22 val23
kk11  kk12  kk13   k3   def   def    val32 val33
kk21  kk22  kk23   k1   def   def    val12 val13
kk21  kk22  kk23   k2   def   def    val22 val23

I have two entries just like for the inner join + entries for all other key range values of A (k1, k2 and k3) with default values (that I need to set) for columns of B. I tried a right join but then I only have default entries once in the result and not for each key of B. Can you help me in the right direction to achieve this ?

Christian

Answer 1

select D.BKey1,
       D.BKey2,
       D.BKey3,
       D.AKey,
       coalesce(B.Col5, 'def') as Col5,
       coalesce(B.Col6, 'def') as Col6,
       A.ACol2,
       A.ACol3
from (select B.BKey1, B.BKey2, B.BKey3, A.AKey
      from TableA as A
        cross join (select distinct BKey1, BKey2, BKey3
                    from TableB
                   ) as B
     ) as D
  inner join TableA as A
    on A.AKey = D.AKey
  left outer join TableB as B
    on B.BKey1 = D.BKey1 and 
       B.BKey2 = D.BKey2 and 
       B.BKey3 = D.BKey3 and 
       B.AKey = D.AKey

For test:

with TableA(AKey, ACol2,  ACol3) as
(
select 'k1',   'val12',  'val13' union all
select 'k2',   'val22',  'val23' union all
select 'k3',   'val32',  'val33'
),
TableB(BKey1, BKey2, BKey3,  AKey, Col5,  Col6) as
(
select 'kk11',  'kk12',  'kk13',   'k1',   'val15', 'val16' union all
select 'kk11',  'kk12',  'kk13',   'k2',   'valx',  'valy'  union all
select 'kk21',  'kk22',  'kk23',   'k3',   'val25', 'val26'
)

select D.BKey1,
       D.BKey2,
       D.BKey3,
       D.AKey,
       coalesce(B.Col5, 'def') as Col5,
       coalesce(B.Col6, 'def') as Col6,
       A.ACol2,
       A.ACol3
from (select B.BKey1, B.BKey2, B.BKey3, A.AKey
      from TableA as A
        cross join (select distinct BKey1, BKey2, BKey3
                    from TableB
                   ) as B
     ) as D
  inner join TableA as A
    on A.AKey = D.AKey
  left outer join TableB as B
    on B.BKey1 = D.BKey1 and 
       B.BKey2 = D.BKey2 and 
       B.BKey3 = D.BKey3 and 
       B.AKey = D.AKey

Result:

BKey1 BKey2 BKey3 AKey Col5  Col6  ACol2 ACol3
----- ----- ----- ---- ----- ----- ----- -----
kk11  kk12  kk13  k1   val15 val16 val12 val13
kk11  kk12  kk13  k2   valx  valy  val22 val23
kk11  kk12  kk13  k3   def   def   val32 val33
kk21  kk22  kk23  k1   def   def   val12 val13
kk21  kk22  kk23  k2   def   def   val22 val23
kk21  kk22  kk23  k3   val25 val26 val32 val33

Test it here.