select
case name
when 'aa' then 'hello aa'
when 'bb' then 'hello bb'
else name
end as name,
cast(name as varchar(50)) as '姓名',
convert(varchar(50),name) as '名字'
from students
但是注意要想在sql中将字符串转换成时间，要将字符串的格式改变成时间格式
