complicated SQL:how to using a query to compute rank of order(Outstanding of Class 1)

[bbaaking]

hi Rabbit,
I googled "having" usage, and I tried this statement:
select TCID,ID v1, endTime from service group by TCID having v1>20
It is right. So there must be something wrong with "case when".
But how to fix it. I have no idea. Can you give me a further hint?

[Rabbit]

In the HAVING clause, you just need to get rid of the CASE statement and use COUNT(*) < 4