选择虚拟列作为百分比

Question

有没有办法选择虚拟列作为另一列的百分比，记录的最大值是100％？

 
Example: 

+------------------------------+ 
| tbl_test      | 
+------------------------------+ 
| id | col_x | value | percent | 
+------------------------------+ 
| 1 |  a |  2 |  25 | 
| 2 |  b |  5 | 62.5 | 
| 3 |  c |  8 |  100 | 
| 4 |  d |  3 | 37.5 | 
+------------------------------+ 

正如你可以看到8成为100％，其余被计算为8

SELECT * ,() as percent 
FROM tbl_test 

Answer 1

一个百分比做这样的事情，你首先需要知道100％是什么：

SELECT *, value/(SELECT MAX(value) AS hperc FROM tbl_test)*100 AS percent 
FROM tbl_test; 

：

SELECT MAX(value) AS hperc FROM tbl_test; 

一旦知道，你可以通过这个100％除以其他值

Answer 2

这是如何在TSQL中完成的：

select @max = max(value) from tbl_test 
select *, cast(value/@max * 100 as decimal(18,2)) as [percent] 
from tbl_test