select deptno,concat((count(empno)/(select count(empno) from emp))*100,'%') 人数占比

from emp

group by deptno #前三句是查询语句

into outfile 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/t1.csv'

fields terminated by ','

lines terminated by '\r\n'; #后三句是保存语句（只能保存到安全路径）

# '\r\n'回车分隔符；'\t\n'Tab分隔符