SQL - 两张表之间的区别计数

Posted 2021-05-03

我对我认为是比较简单的剧本有一个思维上的误区。希望是我把逻辑想得太简单了。

我想做的是在一个不同的列上执行两个计数，这个列是直连的。

我想要的是

    count(a.book_id) as count_of_books
    count(b.book_ref_number) as count_of_losses 

预期输出

--------------------------------------------------------
| Book          | count_of_books      | count of losses|
--------------------------------------------------------
|Hunger Games   | 76                  | 31             |
--------------------------------------------------------
|Hop on Pop     | 27                  | 6              |
--------------------------------------------------------
|Pout Pout Fish | 138                 | 43             |
--------------------------------------------------------

我已经尝试了几个不同的脚本。以下是我试过的两个脚本。

   (select count(*) from Inventory_Table x  ) Count1,
   (select count(*) from Loss_table b  ) Count2
   from Inventory_Table x
   right join Loss_table b on b.book_ref_number = x.book_id
   where rownum < 20



   select
   a.book_name,
   count(distinct a.book_id),
   count(b.book_ref_number)
   from Inventory_Table x
   right join Loss_table b  on trim(b.book_ref_number) = trim(a.book_id)

我得到的结果

--------------------------------------------------------
| Book          | count_of_books      | count of losses|
--------------------------------------------------------
|Moby Dick      | 4376                | 2574           |
--------------------------------------------------------

请大家指点一下我的疏忽错误。先谢谢你

答案

and rownum <20 你把结果集限制在20条记录上。

试试这个

select * from (
select
   a.mrch_Nr,
   count(distinct a.fdr_trac_nr),
   count(b.auth_id)
from DATASTORE_FD.DEB_CRD_AUTH_LOG_REC a
right join jordab26.ft b on trim(b.auth_id) = trim(a.fdr_trac_nr)
where a.auth_log_dt between '20200101' and '20200408' 
group by a.mrch_nr
) 
where rownum < 20

另一答案

试试这个，我不确定 rownum < 20. 另外，确保你添加正确的条件组。

select sum(case book_id when null then 0 else 1 end )  count_of_books,
          sum(case book_ref_number when null then 0 else 1 end ) count_of_losses
     from Inventory_Table x
   right join Loss_table b on b.book_ref_number = x.book_id
   where rownum < 20

另一答案

这是你想要的吗？

      Select distinct bookname, 
        count(distinct 
              a.bookid)+sum(
           case when a.bookid IS NULL
           THEN 1 END) ,
         count(distinct b.id) as lossid
     From inventary_table a 
    Left Join
    Loss_table b
    On
    a.bookid=b.book_ref_number

另一答案

SELECT book_name,COUNT(book_id),COUNT(book_ref_id) FROM Inventory_Table right join Loss_table on book_ref_number = book_id GROUP BY book_name。

但是如果你需要库存中的所有账本，而只需要Loss_table中的匹配账本，那么就应该采用左连接。

SELECT book_name,COUNT(book_id),COUNT(book_ref_id) FROM Inventory_Table leftjoin Loss_table on book_ref_number = book_id GROUP BY book_name

另一答案

0

SELECT book_name,COUNT(book_id),COUNT(book_ref_id) FROM Inventory_Table right join Loss_table on book_ref_number = book_id GROUP BY book_name。