ora-00937不是单组分组功能-计数问题

Question

select au_lname, au_fname, count(titles.title)
from titleauthor
join titles ON titles.title_id=titleauthor.title_id
join authors ON authors.au_id=titleauthor.au_id
having COUNT(titles.title) > 2;

I keep receiving the ora-00937 error, but I'm not entirely clear why it's not a single-group group function. Anyone have any idea?

Answer 1

You simply need a group by :

select a.au_lname, a.au_fname, count(*)
from titleauthor ta join
     authors a
     ON a.au_id = ta.au_id
having COUNT(*) > 2;

In addition, you don't need to join to titles -- unless some of the titles are actually NULL or duplicated (which seems unlikely).