I want to select from a table only when a field repeats more than once. For this I have:

Select title, Count(*) As Cnt From poss_titles where Cnt > 1 Group By Title Order By Cnt desc

But it says invalid column name cnt. How should I refer to this dynamic field?
Also, I only really want titles which dont exist in another table. I believe a left join is required for this but I'm not too sure how to do it.
Can anyone offer me some pointers?

You can't use the alias in the boolean test plus you should use a having clause to test the count(*) and not the where clause.

Select title, count(*) As Cnt 
From poss_titles 
Group By title
Having count(*) > 1 
Order By count(*) desc

as for only showing fields that don't exist in another table you can use exists condition.

Select title, count(*) As Cnt 
From poss_titles pt
Where not exists (select title from other_table ot where ot.title = pt.title)
Group By title
Having count(*) > 1 
Order By count(*) desc
commented: Well done +11
commented: Very Helpful. Instant solve +0

That's fantastic. Thanks a lot : )