sql query date time

Try this

select * from <TableName>
where convert(nvarchar,OnDateTime,108) between '18:00:00' and '23:00:00'
and convert(nvarchar,OffDateTime,108) between '18:00:00' and '23:00:00'
and convert(nvarchar,OnDateTime,101) between '04/02/2012' and '12/01/2012' 
and convert(nvarchar,OffDateTime,101) between '04/02/2012' and '12/01/2012' 

Select allOpen in new window

Or

select * from <TableName>
where (convert(nvarchar,OnDateTime,108) >= '18:00:00' and convert(nvarchar,OffDateTime,108) <= '23:00:00')
and (convert(nvarchar,OnDateTime,101) >= '04/02/2012' and  convert(nvarchar,OffDateTime,101) <= '12/01/2012')

Select allOpen in new window

Do OnDateTime and OffDateTime represent periods that you need to see if they intersect with the periods you are looking at?

If OnDateTime = '2012-04-02 17:00:00' AND OffDateTime = '2012-04-03 02:00:00' would it show up?
Are both fields on the same row in the table?

For instance, we use similar fields when doing resource tracking, and need to see whomever had a resource during each shift.  There are four options:
1. Have it assigned prior to shift and keep until after shift
2. Have it assigned prior to shift and return it during shift.
3. Have it assigned during shift and return after shift
4. Have it assigned during shift and returned during shift.

Which conditions are you looking for?

OndateTime                        OffDateTime                    Data
2012-04-02 18:00:00          2012-10-02 21:00:00        test 1
2012-04-02 19:00:00          2012-10-02 21:00:00        test 2
2012-04-02 20:00:00          2012-10-02 21:00:00        test 3
2012-04-02 21:00:00          2012-10-02 22:00:00        test 4
2012-04-03 18:00:00          2012-10-02 23:00:00        test 5

If I'm querying the database at 2012-04-02 12:00:00 (getdate())  it should not return anything as you can see.

But if I'm querying at  2012-04-03 19:01:00   i should get  test1 and test 2

I hope this clarifies the question

Perfect!
Thank you for the quick solution.