Re: Substract queries

[Niklas Johansson <spot(at)tele2(dot)se>]

On 22 maj 2008, at 17.15, Nacef LABIDI wrote:
> I was wondering how can I substract result between select queries.  
> I mean I want to issue a query that does this :
> (select * from mytable where condition1) - (select * from mytable  
> where condition2)

If you (as implied above) query the same table in both cases, just do:

SELECT * FROM mytable WHERE condition1 AND NOT condition2

Otherwise, use EXCEPT:

SELECT * FROM mytable1 WHERE condition1
EXCEPT
SELECT * FROM mytable2 WHERE condition2

in which case both queries must return the same type of rows.




Sincerely,

Niklas Johansson