we can use having clause without group bu clause .but it 
will act as where clause

we can use, but select columns and having columns should 
use with aggregare functions

ex:
select max(empid), min(marks)
from employee
having max(empid_id)>100

select max(empno) from dbo.Employee having count(EmpNo)=9

it has no meaning so it will show zero record

HAVING Clause
Specifies a search condition for a group or an aggregate. 
HAVING is usually used with the GROUP BY clause. When GROUP 
BY is not used, HAVING behaves like a WHERE clause.

Reference:
http://msdn.microsoft.com/en-us/library/aa259187
(SQL.80).aspx