如何在t-sql的表末尾添加總行？

Question

我需要添加一總和作為表的最后一行。 例如：

   book_name   |   some_row1   |   some_row2   |   sum   
---------------+---------------+---------------+----------
    book1      |   some_data11 |   some_data12 |   100
    book2      |   some_data21 |   some_data22 |   300
    book3      |   some_data31 |   some_data32 |   500
 total_books=3 |   NULL        |   NULL        |   900

我怎樣才能做到這一點？ （T-SQL）

Answer 1

您可以使用union all ：

select book_name, some_row1, some_row2, sum 
from table t
union all
select cast(count(*) as varchar(255)), null, null, sum(sum)
from table t;

但是， count(*)不會提供表中可用no of rows ，如果book_name也具有null值，那么您需要count(book_name)而不是count(*) 。

Answer 2

嘗試使用ROLLUP

SELECT  CASE 
            WHEN (GROUPING([book_name]) = 1) THEN 'total_books'
            ELSE [book_name] END AS [book_name],some_row1, some_row2
        ,SUM(]sum]) as Total_Sales
From    Before
GROUP BY
        [book_name] WITH ROLLUP

Answer 3

我發現grouping sets比rollup更靈活。 我可以這樣寫：

select coalesce(book_name,
                replace('total_books=@x', '@x', count(*))
               ) as book_name,
       col2, col3, sum(whatever)
from t
group by grouping sets ( (book_name), () );

嚴格來說，帶有CASE的GROUPING函數比COALESCE()更好。 但是，分組鍵上的NULL值很少。