时间比较方式等

alter user scott account unlock;

 

时间比较方式：

select * from emp where to_char(hiredate,'yyyy-mm-dd'')>'1982-01-01';

select * from emp where to_char(hiredate,'yyyy')='1980';

select * from emp where to_char(hiredate,'mm')='05';

 

select name, sal*13+nvl(comm,0)*13 年薪  from emp order by 年薪 desc;