SQL中'）'附近的语法不正确

Question

I am a newbie in SQL and I do not know what is wrong with this code :

select 
    t.title, pub.pub_name 
from 
    titles t 
inner join 
    publishers pub on t.title_id = pub.pub_id
where 
    t.title_id in (select title_id 
                   from
                       (select t.title_id, sum(s.qty) 
                        from titles t 
                        inner join sales s on t.title_id = s.title_id
                        group by t.title_id
                        having sum(s.qty) > 20)
                  )

Do you folks know why this is not working?

Answer 1

It seems that you are using SQL Server, and your error is because you don't use alias for your table in subquery. You could fix it by name an alias for it.

But IMO you should rewrite your query to this simple version:

SELECT t.title , pub.pub_name 
FROM titles t 
INNER JOIN publishers pub 
ON t.title_id = pub.pub_id
WHERE t.title_id IN (
    SELECT title_id 
    FROM titles t 
    INNER JOIN sales s 
    ON t.title_id = s.title_id
    GROUP BY t.title_id
    HAVING SUM(s.qty) > 20
);

Answer 2

You should add alias to your Sub Query

select
  t.title,
  pub.pub_name
from
  titles t
  inner join publishers pub on t.title_id = pub.pub_id
where
  t.title_id in (
    select
      title_id
    from(
        select
          t.title_id,
          sum(s.qty)
        from
          titles t
          inner join sales s on t.title_id = s.title_id
        group by
          t.title_id
        having
          sum(s.qty) > 20
      ) as t_id
  )

Or else it will throw an error at ) with something like this

Every derived table must have its own alias

A good way to test your queries is to use validators online

http://sqlfiddle.com/