Oracle函数

--小写
select lower (‘HAPPY‘) "Lowercase" from dual

--大写
select upper（‘last name‘）"Uppercase" from dual

--首字母大写
select initcap (‘the socp‘) "Capitals" from dual

select concat (‘happy‘,‘boy‘) from dual

--两个日期相差的月数
select months_between
(
to_date(‘02-02-1995‘,‘MM-DD-YYYY‘),
to_date(‘01-01-1995‘,‘MM-DD-YYYY‘)
) "Months"
from dual

--向指定日期中加上若干月数

select to_char(add_months(HIREDATE,1),‘DD-MON-YYYY‘) "Next month"
from  emp
where ENAME=‘WARD‘;

--隐式转换
select * from emp
where hiredate=‘17-12月-80‘

 select ename,empno,
      decode (ename,‘SMITH‘,1,
      ‘ALLEN‘,2,
      ‘WARD‘,3,
      ‘JONES‘,4) "Location"
      from emp
      where empno<7600
      order by empno,"Location"