Oracle查询练习01

1 . 查询工资大于12000的员工姓名和工资

select last_name, salaryfrom employeeswhere salary > 12000

2 . 查询员工号为176的员工的姓名和部门号

select last_name, department_idfrom employeeswhere employee_id = 176

3 . 选择工资不在5000到12000的员工的姓名和工资

select last_name, salaryfrom employeeswhere salary not between 5000 and 12000

4 . 选择雇用时间在1998-02-01到1998-05-01之间的员工姓名，job_id和雇用时间

select last_name, job_id, hire_datefrom employeeswhere hire_date between '1-2月 -1998' and '1-5月 -1998'

5 . 选择在20或50号部门工作的员工姓名和部门号

select last_name, department_idfrom employeeswhere department_id in (20, 50)

6 . 选择在1994年雇用的员工的姓名和雇用时间

select last_name, hire_datefrom employeeswhere hire_date like '% -94'

7 . 选择公司中没有管理者的员工姓名及job_id

select last_name, job_idfrom employeeswhere manager_id is null

8 . 选择公司中有奖金的员工姓名，工资和奖金级别

select last_name, salary, commission_pctfrom employeeswhere commission_pct is not null

9 . 选择员工姓名的第三个字母是a的员工姓名

select last_namefrom employeeswhere last_name like '__a%'

10 . 选择姓名中有字母a和e的员工姓名

select last_namefrom employeeswhere last_name like '%a%' and last_name like '%e%'

11 . 显示系统时间

select to_char(sysdate, 'yyyy-mm-dd hh:mi:ss') from dual;

12 . 查询员工号，姓名，工资，以及工资提高百分之20%后的结果（new salary）

select employee_id, last_name, salary, salary * 1.2 "new salary"from employees;

13 . 将员工的姓名按首字母排序，并写出姓名的长度（length）

   select last_name, length(last_name)from employeesorder by last_name

14 . 查询各员工的姓名，并显示出各员工在公司工作的月份数（worked_month）。

   select last_name, months_between(sysdate, hire_date) worked_monthfrom employees

15 . 查询员工的姓名，以及在公司工作的月份数（worked_month），并按月份数降序排列

select last_name, months_between(sysdate, hire_date) worked_monthfrom employeesorder by worked_month desc

16 . 做一个查询，产生下面的结果

<last_name> earns <salary> monthly but wants <salary*3>Dream SalaryKing earns $24000 monthly but wants $72000select last_name || ' earns ' || salary || ' monthly but wants ' || salary * 3from employees

17 . 使用decode函数，按照下面的条件：
job grade
AD_PRES A
ST_MAN B
IT_PROG C
SA_REP D
ST_CLERK E
Others F
产生下面的结果
Last_name Job_id Grade
king AD_PRES A

select last_name, job_id, decode(job_id, 'AD_PRES', 'A',                                         'ST_MAN', 'B',                                         'IT_PROG', 'C',                                         'SA_REP', 'D',                                         'ST_CLERK', 'E',                                         'F') GRADEfrom employees

18 . 将第7题的查询用case函数再写一遍。

select last_name, job_id, case job_id when 'AD_PRES' then 'A'                                      when 'ST_MAN' then 'B'                                      when 'IT_PROG' then 'C'                                      when 'SA_REP' then 'D'                                      when 'ST_CLERK' then 'E'                                      else 'F'                           end            from employees

19 . 查询公司员工工资的最大值，最小值，平均值，总和

Select max(salary), min(salary), avg(salary), sum(salary)From employees

20 . 查询各job_id的员工工资的最大值，最小值，平均值，总和

Select job_id, max(salary), min(salary), avg(salary), sum(salary)From employeesGroup by job_id

21 . 选择具有各个job_id的员工人数

Select job_id, count(employee_id)From employeesGroup by job_id;

22 . 查询员工最高工资和最低工资的差距（DIFFERENCE）

Select max(salary) – min(salary) differenceFrom employees

23 . 查询各个管理者手下员工的最低工资，其中最低工资不能低于6000，没有管理者的员工不计算在内

Select manager_id, min(salary)From employeesWhere manager_id is not nullGroup by manager_idHaving min(salary) >= 6000

24 . 查询所有部门的名字，location_id，员工数量和工资平均值

Select department_name, location_id, count(employee_id), avg(salary)From employees e join departments dOn e.department_id = d.department_idGroup by department_name, location_id