Question

These two queries return different order counts and it’s not entirely clear as to why. The first where clause is the accepted correct version:

where
year(OrderDate) = 2011
and MONTH(OrderDate) = 8
and DAY(OrderDate) = 3

but if I say something very similar:

WHERE 
io.OrderDate >= '2011-08-03 00:00:00' 
and io.OrderDate <= '2011-08-03 11:59:59'

I get a completely different record count. Is there something I’m doing wrong in date formatting or is there something I’m missing in logic? I’d prefer to say the latter as it’s a little easier to use IMHO.

Answer 1

EDIT:

The new answer I would recommend combines my original (as displayed below) with the comments made by Mikael and Alex.

WHERE 
io.OrderDate >= '2011-08-03 00:00:00' 
and io.OrderDate < '2011-08-04 00:00:00'

Should provide the desired result.

---

The second query is only looking from Midnight to Noon. (00:00:00 – 11:59:59 is twelve hours)

WHERE 
io.OrderDate >= '2011-08-03 00:00:00' 
and io.OrderDate <= '2011-08-03 23:59:59'

Should fix it.

@Alex answer has a point as well. Milliseconds count (depending on whether or not your particular table includes them).

WHERE 
io.OrderDate >= '2011-08-03 00:00:00.000' 
and io.OrderDate <= '2011-08-03 23:59:59.999'

Would include any additional records missed