Question

I’m trying to find a good, efficient way to run a query like this:

SELECT *
  FROM tableA a
 WHERE    a.manager IN (    SELECT id
                                 FROM tableB b
                           CONNECT BY PRIOR b.id = b.manager_id
                           START WITH b.id = 'managerBob')
       OR a.teamLead IN (    SELECT ID
                               FROM tableB b
                         CONNECT BY PRIOR b.ID = b.manager_id
                         START WITH b.ID = 'managerBob')
       OR a.creator IN (    SELECT id
                              FROM tableB b
                        CONNECT BY PRIOR b.id = b.manager_id
                        START WITH b.id = 'managerBob')

As you can see, I’m trying to use multiple WHERE clauses, but each clause is using the same dataset on the right-hand side of the equation. It seems to run very slowly if I use more than one clause, and I’m pretty sure that it’s because Oracle is running each subquery. Is there a way to make something like this work?

SELECT *
  FROM tableA a
 WHERE    a.manager, 
          a.teamLead, 
          a.creator in (    SELECT id
                                 FROM tableB b
                           CONNECT BY PRIOR b.id = b.manager_id
                           START WITH b.id = 'managerBob')

By the way, I’m sorry if this is something I could have Googled, I’m not sure what to call this.

Answer 1

Subquery factoring may help:

WITH people AS
(    SELECT id
       FROM tableB b
    CONNECT BY PRIOR b.id = b.manager_id
      START WITH b.id = 'managerBob'
)
SELECT *
  FROM tableA a
 WHERE    a.manager IN (SELECT id FROM people)
       OR a.teamLead IN (SELECT id FROM people)
       OR a.creator IN (SELECT id FROM people)