create table tb(Department varchar(10), counter int)
insert into tb values('A',           10 )
insert into tb values('B',           68 )
insert into tb values('C',           45 )
insert into tb values('D',           23 )
insert into tb values('E',           20 )
insert into tb values('F',           10 )
insert into tb values('G',           10 )
insert into tb values('H',           30 )
insert into tb values('I',           90 )
insert into tb values('J',           100)
go

select t1.* , [percent] = cast(cast((t1.counter*1.0/t2.cnt)*100 as decimal(18,2)) as varchar(5)) + '%'  from 
(select Department , sum(counter) counter from tb group by Department) t1,
(select sum(counter) cnt from tb) t2

drop table tb
/*
Department counter     percent 
---------- ----------- ------- 
A          10          2.46%
B          68          16.75%
C          45          11.08%
D          23          5.67%
E          20          4.93%
F          10          2.46%
G          10          2.46%
H          30          7.39%
I          90          22.17%
J          100         24.63%

（所影响的行数为 10 行）
*/

------解决方案--------------------
SQL code
create table tb(Department varchar(10), counter int) 
 insert into tb values('A',       10 ) 
 insert into tb values('B',       68 ) 
 insert into tb values('C',       45 ) 
 insert into tb values('D',       23 ) 
 insert into tb values('E',       20 ) 
 insert into tb values('F',       10 ) 
 insert into tb values('G',       10 ) 
 insert into tb values('H',       30 ) 
 insert into tb values('I',       90 ) 
 insert into tb values('J',       100) 
 go 
  
 select Department , sum(counter) counter ,  
    [percent] = cast(cast((sum(counter)*1.0/(select sum(counter) from tb))*100 as decimal(18,2)) as varchar(5)) + '%'  
 from tb group by Department 
  
 drop table tb 
 /* 
 Department counter   percent  
 ---------- ----------- -------  
 A      10      2.46% 
 B      68      16.75% 
 C      45      11.08% 
 D      23      5.67% 
 E      20      4.93% 
 F      10      2.46% 
 G      10      2.46% 
 H      30      7.39% 
 I      90      22.17% 
 J      100     24.63% 
  
 （所影响的行数为 10 行） 
 */


------解决方案--------------------
create table DEPARTMENT(Department varchar(50),counters int)
insert into DEPARTMENT select 'A',10
insert into DEPARTMENT select 'B',68