SQL查詢添加備用空白的記錄

Question

我使用下面的查詢從SQL Server顯示記錄

select * from orders 

目前該查詢顯示全部100個記錄的數據庫，我需要的是，而不是100它應該顯示200條記錄（所以備用空白記錄是好的）可以這樣做嗎？

Answer 1

-- sample table 
declare @Order table 
( 
    orderid int, 
    qty int 
) 

-- add some data 
insert into @Order 
select 1, 10 union all 
select 2, 20 union all 
select 3, 30 

-- cross join the query against two rows  
select case D.N when 1 then O.orderid end as orderid, 
     case D.N when 1 then O.qty end as qty 
from @Order as O 
    cross join (select 1 union all select 2) as D(N) 
order by O.orderid, D.N 

結果：

orderid  qty 
----------- ----------- 
1   10 
NULL  NULL 
2   20 
NULL  NULL 
3   30 
NULL  NULL