Finding missing records.

Question

Hi, I have a table that contains a person contact for a given centre. There may be many types of contact at a centre. However there maybe only say2 mandatory type of contact that must be setup for a centre. If one of these mandatory contacts is not setup then the SQL should list out this centre and the missing mandatory contact type.
For example, imagine there are 10 sales offices. There can be all types of people work there, receptionist, cleaner, CEO, finance manager(FM) etc. However we just want to check each centre if there is a missing CEO or FM.
I managed to write two SQL statements.
1.     This is a Cartesian/equi-join that shows who SHOULD be at each centre eg
select *
from CENTRES c, staff_roles sr
where sr.STAFF_ROLE in ('CEO','FM', )
order by c.centre_no
Centre     Person Role Code
‘001’     CEO
‘001’      FM
‘002’     CEO
‘002’     FM
Etc.
2.     I then managed to write another SQL to show who is ACTUALLY there, eg
select distinct centre_no, staff_role
from centrestaff
where staff_role in ('CEO','FM', )
order by centre_no, staff_role
‘001’     CEO
‘002’     CEO
‘002’     FM
So you can see centre 001 is missing a Finance Manager ‘FM’ and should be shown on the final report.
3.     My last thing was to find a way to link these two SQL together in some type of OUTER join and to do a select on the right side where the centre and role code are NULL values.
select *
from (select *
from CENTRES c, staff_roles sr
where sr.STAFF_ROLE in ('CEO','FM', )
order by c.centre_no)
right OUTER JOIN centrestaff NCS ON c.CENTRE_NO = ncs.CENTRE_NO
and ncs.staff_role in ('CEO','FM', )
order by ncs.centre_no, ncs.staff_role
However I keep getting message ORA-00942: table or view does not exist.
Possible the problem is I am trying to refer to the centre_no in the encapsulating SQL FROM statement. Is there a way round this?
thanks

Answer 1

Hi,
You can do that with a Partitioned Outer Join , like this:
WITH  target_staff_roles     AS
     SELECT     staff_role
     FROM     staff_roles
     WHERE     staff_role     IN ('CEO', 'FM')
SELECT    t.staff_role
,       a.*
FROM           target_staff_roles     t
LEFT OUTER JOIN      (
                       SELECT  c.*
               ,          s.staff_role
               FROM    centres          c
               JOIN    staff_roles     s  ON     c.centre_no     = s.centre_no
                   )               a     PARTITION BY (a.centro_no)
                               ON t.staff_role = a.staff_role
WHERE     a.staff_role     IS NULL
ORDER BY  a.centre_no
,            t.staff_role
;If you'd care to post CREATE TABLE and INSERT statements for your sample data, then I could test it.
The reason you were getting that error was that you referenced c.centro_no in the join condition of the main query, but table c is not used in hte main query. The only "tables" in the main query are ncs and the unnamed in-line view.
Edited by: Frank Kulash on Mar 9, 2012 10:52 AM