Oracle根据数据字典的查询练习，oracle数据字典
根据数据字典，查询当前用户下有哪些表 select * from all_tables t where t.OWNER ='HR'; 查询所有员工编号，员工姓名、邮件、雇佣日期、部门、部门详细地址信息 select e.employee_id,e.first_name||e.last_name as full_name, e.email,e.hire_date,
d.department_name,m.first_name||m.last_name as manager_name,
street_address,city,state_province
from employees e,employees m,departments d,locations l
where e.manager_id=m.employee_id
and e.department_id=d.department_id
and d.location_id=l.location_id; 查询1997年入职员工员工编号，员工姓名，雇佣日期，工龄(保留2位小数)、按照First_Name升序排列
select employee_id,first_name,last_name,round((sysdate-hire_date)/365,2) as work_age
from employees
where to_char(hire_date,'yyyy') = 1997
order by first_name
显示姓、薪水，佣金(commission) ，然后按薪水降序排列
select first_name,last_name,salary,commission_pct
from employees
order by salary desc
显示姓名、薪水，佣金，佣金为空的，统一加上0.05;其余的加上0.03，按照薪资降序、变更后佣金升序排列
select first_name,last_name,salary,commission_pct, NVL2(commission_pct,commission_pct+0.03,0.05) NEW_COMMISSION_PCT
from employees
order by NEW_COMMISSION_PCT asc , salary desc 显示名字以J、K、L、M开头的雇员
select *
from employees
where substr(first_name,1,1) in ('J','K','L','M') or substr(last_name,1,1) in ('J','K','L','M')
显示员工姓名，薪水，调整后薪水(按部门调整：IT提升30%,Salse 提升50%、其余部门提升20%);按照调整后薪水升序排列
select first_name,last_name,salary,department_name,
case department_name
when 'IT' then 1.30*salary
when 'Sales' then 1.50*salary
else 1.20*salary
end "REVISED_SALARY"
from employees left join departments on
employees.department_id = departments.department_id
order by REVISED_SALARY
显示在每月中旬雇佣的员工,显示姓名，雇佣日期
select first_name,last_name,hire_date
from employees
where TO_CHAR(hire_date, 'DD') between 11 and 20