sql - 从没有变量的单列计算百分比

Question

我在sql server中有下表

HEAD    | COL1  | COL2
------------------------
MARKS   | 546   | 798
TOTAL   | 1000  | 1000
PERCENT | NULL  | NULL

我想通过查询填充如下结果。请帮我

HEAD    | COL1  | COL2
------------------------
MARKS   | 546   | 798
TOTAL   | 1000  | 1000
PERCENT | 54.6  | 79.8

Answer 1

update tablename set
col1 = c1, col2 = c2 from
(
Select x.col1*100./y.col1 c1, x.col2*100./y.col2 c2 from
(select * from TableName where head='mark') x
cross join 
(select * from TableName where head='total') y
 ) z
where head = 'percent';

Answer 2

不会接受你的表结构。它是颠倒的，伤害了我的眼睛。为您的表结构编写解决方案只会治愈症状，我正在尝试治愈真正的问题。

CREATE TABLE Table1
([head] varchar(10), [marks] INT, [total] INT, [pct] as cast(100.0*marks / total as numeric(4,1)))

INSERT INTO Table1(head, marks, total)
VALUES ('Col1', 546, 1000),('Col2', 798, 1000)

SELECT head, marks, total FROM Table1

结果：

head  marks  total  pct
Col1  546    1000   54.6
Col2  798    1000   79.8