加括號的負值減去

Question

時如何花括號添加到負值，這將是兩列相減的結果，

假設我有三列

 A  B   result(B-A) 
----------------------------------------- 
     1  4    3 

     2  1   -1 [should be displayed as (1) not -1] 

     9  3   (6) 
----------------------------------------- 
total 3  5   (4) 

如何在選擇查詢中做到這一點？

Answer 1

如果你使用SQL Server試試這個：

select case 
     when (b-a) < 0 then '{ ' + substring(CONVERT(NVARCHAR,(b-a)),2,2) + '}' 
     else CONVERT(nvarchar(max),(b -a)) END as result 
from table 

Answer 2

查詢：

SQLFIddleExample

SELECT 
t1.A, 
t1.B, 
CASE WHEN t1.B-t1.A<0 
     THEN '('+CAST((t1.B-t1.A)*-1 as varchar(5))+')' 
     ELSE CAST(t1.B-t1.A as varchar(5)) END AS result 
FROM tbl t1 

結果：

| A | B | RESULT | 
------------------ 
| 1 | 4 |  3 | 
| 2 | 1 | (1) | 
| 9 | 3 | (6) |