SQL SELECT表达式-在3个表之间进行选择

Question

I have tables

T1:

T1ID

1000
1001
1002
1003

T2:

T2ID     T1ID

W1       1000
W2       1000
W3       1001
W4       1002
W5       1003

T3:

T3ID   STATUS   T2ID

T1     CLOSE    W1
T2     CLOSE    W1
T3     INPRG    W3
T4     INPRG    W3
T5     CLOSE    W5
T6     INPRG    W5

I want to make expression to get as result only 1000 and 1002 from T1. As result from T1 select I want to get records that either in T2 have T2 records for which all T3 records are in CLOSE status or T2 records do not have T3 records at all.

So 1000 has W1 which has all T3 records in CLOSE and W2 which does not have T3 records. Also 1002 have W4 record which does not have T3 records. So they must be selected.

1001 must not be selecet beacuse it has W3 record for which all T3 records are not CLOSEd. 1003 also must not be selected because it has W5 for which all T3 records are not closed.

It is little tricky for me.

Thank you

Answer 1

Select distinct t1.id
From   t1
       Inner join
       T2 on t1.id=t2.t1id
       Left join
       (Select t3.t3id 
        from T3 
        where t3.status <> 'CLOSE') t3a on t3a.t3id=t2.t3id and t3.t3id is null

Written on a tablet so please forgive/correct the capitalisation.

Answer 2

So you want all records from T1 where there are either ONLY closed T3 records, or no T3 records, where T3 is linked to T1 via T2. Conversely, you want all T1 records EXCEPT those where you have non-closed T3 records.

Expressing it both ways gives different ways to write the same query. For example you could do

SELECT t1.id
FROM t1
where not exists(
  select * 
  from t2
    inner join t3
      on t2.id = t3.t2id
  where t3.status <> 'CLOSE'
  )

Alternatively you could do

select t1.id
from t1
EXCEPT
select t1.id
from t1
  inner join t2
    on t1.id = t2.t1id
  inner join t3
    on t2.id = t3.t2id
where t3.status <> 'CLOSE'

You can ask SQL Server Management Studio to tell you which one is more efficient - they may well end up executing with the same query plan.

(not tested but I think the syntax above is ok)