select emp_name as A from emp where A = 'S0207069' 不行。
select emp_name as A from emp where emp_name = 'S0207069' 可以的。
select emp_name as A from emp order by A 可以。
select emp_name as A from emp where A = 'S0207069' 不行。
select emp_name as A from emp where emp_name = 'S0207069' 可以的。
select emp_name as A from emp order by A 可以。