带有别名的 GROUP BY 子句？

Question

有谁知道为什么我无法在此查询中对TotalSales 进行分组，如果可以，我该如何解决：

select coalesce(Author_ID, 'All Authors') as Author_ID
, case when Author_ID  is null then ' ' else coalesce(Book_ID, 'All Books') end as Book_ID
, TotalQuantity  
, coalesce(TotalSales, 'No Sales') as TotalSales   
from (    
     select  author_id as Author_ID 
            , book_id as Book_ID
            ,  sum(quantity) as TotalQuantity  
            ,  sum(quantity * order_price) as TotalSales   
            from a_bkinfo.book_authors   
            join a_bkorders.order_details using (book_id)
            where author_sequence = 1           
            group by Author_id, Book_ID, TotalSales with rollup
     ) tbl;

当作者没有图书销售时，我想在 TotalSales 下包含“无销售”。这是更新的版本。我不肯定这是正确的，但我确实有输出似乎可以解决问题。这里是：

select coalesce(Author_ID, 'All Authors') as Author_ID
, case when Author_ID is null then ' ' else coalesce(Book_ID, 'All Books') end as Book_ID 
, NumOrders 
, coalesce(TotalSales, 'No Sales') as TotalSales
     from ( select author_id as Author_ID 
            , book_id as Book_ID
            , count(Distinct order_id) AS NumOrders
            ,(Select sum(quantity * order_price) from a_bkorders.order_details) as TotalSales
         from a_bkorders.order_headers
         join a_bkorders.order_details using (order_id) 
         join a_bkinfo.book_authors using (book_id)  
        where author_sequence = 1        
         group by Author_ID, Book_ID, TotalSales with rollup) tbl;

Answer 1

更新2

1. 您似乎不需要在 GROUP BY 中包含 TotalSales。查看您的查询，这没有任何意义。只需将其从内部选择中删除即可。

2. 要包含尚未售出的书籍，您必须使用外连接

话虽如此，您的查询可能看起来像

SELECT COALESCE(author_id, 'All Authors') author_id
     , COALESCE(book_id, IF(author_id IS NULL, 'All Books', 'Subtotal')) book_id
     , COALESCE(total_quantity, 'No books') total_quantity
     , COALESCE(total_sales, 'No Sales') total_sales   
 FROM 
(    
 SELECT author_id 
      , b.book_id 
      , SUM(quantity) total_quantity  
      , SUM(quantity * order_price) total_sales   
   FROM book_authors b LEFT JOIN order_details d
     ON b.book_id = d.book_id
  WHERE author_sequence = 1           
  GROUP BY Author_id, Book_ID WITH ROLLUP  -- you don't need TotalSales here
) q;

样本输出：

+-------------+------------+----------------+------ --------+ |作者_id | book_id |总量 |总销售额 | +-------------+------------+----------------+------ --------+ | 1 | 1 | 12 | 278.50 | | 1 | 3 |没有书|没有销售 | | 1 |小计 | 12 | 278.50 | | 3 | 2 | 5 | 75.75 | | 3 |小计 | 5 | 75.75 | |所有作者 |所有书籍 | 17 | 354.25 | +-------------+------------+----------------+------ --------+

这里是SQLFiddle演示

Answer 2

这就是它的工作原理（顺序）：

1. FROM 子句
2. WHERE 子句
3. GROUP BY 子句
4. HAVING 子句
5. SELECT 子句
6. ORDER BY 子句

在这种情况下，您的别名是在 5 步上创建的，请购买 where works on 2 step。您需要使用计算出的TotalSales 创建子查询，然后在外部查询中使用GROUP。