如何在 sql 中使用 group by 语句时检查多个条件

Question

BOOK_ADOPTION (course:int, sem:int, book_isbn:int)

TEXT (book_isbn:int, booktitle: varchar(50), publisher: varchar(50), author: varchar(50))

List the books which are adopted by the course as well as enrolled by the student.

I am trying this:

select course 
from text 
natural join book_adoption 
group by course 
having count(book_isbn)>1 
  and publisher = 'perason';

and getting an error:

Unknown column 'publisher' in 'having clause'

but the column publisher is there and even the spelling is correct. Can someone help me out with this one?

Answer 1

HAVING clause is for using with aggregating functions (like count) but in the case of publisher you have to simply use the WHERE condition.

select course
from text natural join book_adoption 
where publisher = 'perason'
group by course 
having count(book_isbn)>1;