Question

I have 2 tables :

terminal

id   text
1    abc
2    def
3    dfg

termusage

id  termid   date
1   1        2010-11-01
2   1        2010-10-13
3   2        2010-11-10
4   3        2010-11-13

+ many more records (10 million) approv half are within the date (2010-11-01 and 2010-12-01)

What i want to do is find the terminal.id of the records that do not exist in the termusage table between 2010-11-01 and 2010-12-01

I have looked at select where not exists but nothing is being returned – example

select * from terminal
where not exists (
select * from termusage where date between '2010-11-01' and '2010-12-01' group by termid)

Can anyone please explain how i need to use the where not exists clause or another method !! Cheers

Answer 1

I think that using exists is a faster solution:

select * from terminal t
where not exists (
    select * from termusage tu 
    where (t.id = tu.termid) and (date between '2010-11-01' and '2010-12-01')
)