How can I select from one table where the ID exists in one of two tables, but not in either of other two tables

Question

This sounds confusing, but the idea is quite simple.

I want to get a list of products that have default rates, but a given 'Agent' doesn't have rates for. To do that, I need to select from the below table

    t_Products
|-ProductID-|--Product-|
|   100     | Product1 |
|   101     | Product2 |
|   102     | product3 |
|   103     | product4 |

Where the ID exists in either t_Annual_DefaultCost or t_Daily_DefaultCost

    t_Annual_DefaultCost
|-DefaultID-|-ProductID-|--Cost-|
|    100    |     100   | 24.00 |
|    101    |     101   | 26.00 |

    t_Daily_DefaultCost
|-DefaultID-|-ProductID-|--Cost-|-Days-|
|    100    |     100   | 24.00 |   1  |
|    101    |     100   | 26.00 |   2  |
|    102    |     102   | 22.50 |   2  |
|    103    |     102   | 97.50 |   8  |

But it cannot exist in either t_Annual_AgentCost or t_Daily_AgentCost for the given Agent ID

    t_Annual_AgentCost 
|---CostID--|-ProductID-|-AgentID-|--Cost-|
|    100    |    100    |  10001  | 24.00 |
|    101    |    100    |  10001  | 20.00 |

    t_Daily_AgentCost
|---CostID--|-ProductID-|-AgentID-|--Cost-|-Days-|
|    100    |     100   |  10001  | 24.00 |   1  |
|    102    |     102   |  10002  | 35.00 |   2  |

so for AgentID 10001 the end result should be

|-ProductID-|--Product-|
|   101     | product2 |
|   102     | product3 |

and for AgentID 10002 the end result should be

|-ProductID-|--Product-|
|   100     | product1 |
|   101     | product2 |

I'm currently using the below code to get a list of products that have default rates. But I can't work out how to remove/not get the ones also in the AgentCost tables.

Select 
    distinct a.* 
from 
    t_Products as a
inner join
    ( 
        select 
            DefaultID ,ProductID
        from 
            t_Daily_DefalutCost 

        union 

        select 
            DefaultID , ProductID
        from 
            t_Annual_DefaultCost 
    ) 
    as b on a.ProductID = b.ProductID

Answer 1

If you want to do one Agent at a time, then this is how I would do it:

SELECT
    a.* 
FROM
    t_Products As a
WHERE
    (   EXISTS( SELECT * FROM t_Daily_DefaultCost  As d WHERE d.ProductID = a.ProductID )
     OR EXISTS( SELECT * FROM t_Annual_DefaultCost As d WHERE d.ProductID = a.ProductID )
     )
AND NOT
    (   EXISTS( SELECT * FROM t_Daily_AgentCost    As d 
                WHERE d.ProductID = a.ProductID
                AND   d.AgentID   = @SpecifedAgentID )
     OR EXISTS( SELECT * FROM t_Annual_AgentCost   As d 
                WHERE d.ProductID = a.ProductID
                AND   d.AgentID   = @SpecifedAgentID )
     )

The OR EXISTS s here work pretty much the same as UNION ALL SELECT s would .

Answer 2

I'd use this sort of approach.

select yourfields
from yourtables
where id in 
(

(select id
 from onetable
 union
 select id
 from anothertable)
 except
 (select id
  from yetanothertable
  union
  select id
  from thefinaltable)
)

You can fill in the actual table names.