Question

Table 1 uses joining Table2 for a many to many relationship with Table 3.

Table1

ID

Table2

Table1ID
Table3ID

Table3

ID
SomeData

I want a query that will return only 1 instance of a row from Table1 for a search for multiple Table2.ID’s

Table1:
ID

1

2

3

4

Table 2

1 1

1 2

2 2

2 3

Table3

1 “foo”

2 “bar”

3 “whizz”

4 “bang”

Now I can do a join with a subquery

SELECT * FROM Table1
 WHERE ID in (

SELECT DISTINCT(T1.ID)
FROM Table1 T1 LEFT OUTER JOIN Table2
ON T1.ID = T2.Table1ID
WHERE T2.Table3ID in (1,2)

)

where 1 and 2 are the values I’m searching for.

Now I want to wrap this up in a view so I can query something like:

Select ID, {other stuff from T1} from vwGetData

where Value in (1,2)

Is this possible? hope I made it clear enough

TIA!

Answer 1

If you need some values from Table1 your query should look like this:

select T1.*
from Table1 as T1
where T1.ID in (select T2.Table1ID      
                from Table2 as T2
                where T2.Table2ID in (1, 2))

There is no way to create a view of that and allow you to add in the filter on (1, 2) as a where clause to the query of the view.

Your sample query against the view only retrieves the ID column so to get that information you don’t need to involve Table1 in the query.

select distinct T2.Table1ID as ID
from Table2 as T2
where T2.Table2ID in (1, 2)

You could create a view of that (without the distinct part) but that would not make much sense at all would it?

create view v_Table2
as
select Table1ID, Table2ID
from Table2

Used like this:

select distinct T2.Table1ID as ID
from v_Table2 as T2
where T2.Table2ID in (1, 2)

The view does not really add any value.