oracle学习记录2

-- case的使用
select last_name,
       department_id,
       salary,
       case department_id
           when 10 then salary * 1.1
           when 20 then salary * 1.2
           when 30 then salary * 1.3
           end new_sal
from employees
where department_id in (10, 20, 30);

--decode使用
select last_name,
       department_id,
       salary,
       decode(department_id, 10, salary * 1.1,
              20, salary * 1.2,
              30, salary * 1.3
           ) new_sal
from employees
where department_id in (10, 20, 30);

--字符串拼接
select *
	from employees
	where last_name like '%\_%' escape '\';

-- nvl 使用
select last_name, salary * 12 * (1 + nvl(commission_pct, 0)) year_sal
	from employees;

--to_char的使用
select to_char(sysdate,'yyyy-mm-dd')
	from dual;