Sql 返回作者的姓、名&；有多少本书写得超过1本

两个表是book_数据和author_数据

• book\u data

  有3个字段=

  author\u id

  ，

  book\u name

  ，

  book\u id

• author\u data

  有5个字段=

  author\u id

  ，

  名

  ，

  姓

  ，

  dob

  ，

  社交

我可以在没有计数的情况下跑步，或者：

SELECT first_name, last_name, book_data.author_id
FROM author_data INNER JOIN book_data
                 ON book_data.author_id = author_data.author_id
                 WHERE book_data.author_id = author_data.author_id;

当我加上：

GROUP BY author_id
HAVING COUNT (author_id) > 1)

---

我收到错误消息。

有两件事：{1}当使用JOIN和ON时，不需要编写WHERE子句来连接表。{2} GROUP BY返回“…每个组的一行摘要信息”（请参阅）

测试设置（Oracle 12c）

我们现在有以下作者和书籍：

SQL> select * from authors;
AUTHOR_ID  FIRST_NAME  LAST_NAME  DOB        SOCIAL   
1          fname1      lname1     01-JAN-01  social1  
2          fname2      lname2     02-FEB-02  social2  
3          fname3      lname3     03-MAR-03  social3  


SQL> select * from books;
AUTHOR_ID  BOOK_NAME  BOOK_ID  
1          book1      5000     
2          book2      5001     
2          book22     5002     
3          book3      5003     
3          book33     5004     
3          book333    5005 

{1} 使用连接。。。ON（无WHERE条款）

{2} 将GROUP BY和HAVING添加到查询中

select 
  first_name
, last_name
, B.author_id
from authors A
  join books B on B.author_id = A.author_id 
group by B.author_id
having count( B.author_id ) > 1
;
-- ORA-00979: not a GROUP BY expression

-- works: SELECTed columns are listed in the GROUP BY clause
SQL> select 
  2    first_name
  3  , last_name
  4  , B.author_id
  5  from authors A
  6    join books B on B.author_id = A.author_id 
  7  group by B.author_id, first_name, last_name
  8  having count( B.author_id ) > 1
  9  ;

FIRST_NAME  LAST_NAME  AUTHOR_ID  
fname2      lname2     2          
fname3      lname3     3 

---

在GROUPBY子句中也添加first_name和last_name。您能告诉我们您得到的错误吗？谢谢。这是一个很好的解释。我在stackoverflow上潜伏了很长时间，但这是我的第一个问题。我感谢你的帮助。

SQL> select 
  2    first_name
  3  , last_name
  4  , B.author_id
  5  from authors A
  6    join books B on B.author_id = A.author_id ;

FIRST_NAME  LAST_NAME  AUTHOR_ID  
fname1      lname1     1          
fname2      lname2     2          
fname2      lname2     2          
fname3      lname3     3          
fname3      lname3     3          
fname3      lname3     3  

select 
  first_name
, last_name
, B.author_id
from authors A
  join books B on B.author_id = A.author_id 
group by B.author_id
having count( B.author_id ) > 1
;
-- ORA-00979: not a GROUP BY expression

-- works: SELECTed columns are listed in the GROUP BY clause
SQL> select 
  2    first_name
  3  , last_name
  4  , B.author_id
  5  from authors A
  6    join books B on B.author_id = A.author_id 
  7  group by B.author_id, first_name, last_name
  8  having count( B.author_id ) > 1
  9  ;

FIRST_NAME  LAST_NAME  AUTHOR_ID  
fname2      lname2     2          
fname3      lname3     3