efficiency of SQL query

location:
place lft rgt

Europe	0	99
England	1	10
France	11	20
Italy	21	30
Asia	100	199
London	12	12

staff:
name	locLft


--------------

Edwards	0
Smith	1
Leveil	11
Rossi	21
Lee	12
Chan	100

location uses the Celko hierarchy model.

I wish to retrieve for a location the names of all staff within it and the hierarchy of place associated with that member of staff, eg a query for Europe should return all staff in Europe, and for Lee I wish to return Lee-London, Lee-England, Lee-Europe etc.

I can achieve this using a subquery, ie

SELECT name, place
FROM staff, location
WHERE name IN (SELECT name

               FROM staff, location  
               WHERE place='Europe' And locLft>=location.lft And
locLft<=location.rgt) 
      AND locLft>=lft AND locLft<=rgt 

But is this the most efficient way of doing so?

thanks Received on Fri Apr 09 2004 - 22:56:50 CEST