PLSQL 的简单命令之二

--1.  查询工资大于12000的员工姓名和工资
select first_name,last_name,salary from employees where salary > 12000

--2.    查询员工号为176的员工的姓名和部门号
select first_name,last_name,department_id from employees where job_id = ‘176‘

--3.    选择工资不在5000到12000的员工的姓名和工资
select first_name,last_name,salary from employees where salary < 5000 and salary > 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 first_name,last_name,job_id,hire_date from employees where 
to_char(hire_date,‘yyyy-mm-dd‘)>=‘1998-02-01‘ and to_char(hire_date,‘yyyy-mm-dd‘)<=‘1998-05-01‘; 

--5.    选择在20或50号部门工作的员工姓名和部门号
select first_name,last_name,department_id from employees where 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 first_name,last_name,hire_date from employees where to_char(hire_date,‘yyyy‘)=‘1994‘

--7.    选择公司中没有管理者的员工姓名及job_id
select first_name,last_name,job_id from employees where 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 first_name,last_name,salary,commission_pct from employees where 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 first_name,last_name from employees where first_name like ‘__a%‘ or last_name like ‘__a%‘;

--10.    选择姓名中有字母a和e的员工姓名
select first_name,last_name from employees where  lower(first_name) like ‘%a%‘and 
lower(first_name) like ‘%e%‘ or lower(last_name)like ‘%a%‘ and lower(last_name)like ‘%e%‘;


--单行函数
--1.    显示系统时间(注：日期+时间)
select sysdate from dual

--2.    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,first_name,last_name,salary,salary*1.2 as "NEW SALARY" from employees

--3.    将员工的姓名按首字母排序，并写出姓名的长度（length）
select  substr(first_name,1,1) as FIRSTWORD, length(first_name) as "LENGTH" from employees 
order by substr(first_name,1,1) asc

--4.    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 first_name,last_name,round( months_between(sysdate,hire_date))WORKED_MONTHS from employees

--5.    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 first_name,last_name,round( months_between(sysdate,hire_date))WORKED_MONTHS from employees
 order by WORKED_MONTHS desc 
/*6.    做一个查询，产生下面的结果
<last_name> earns <salary> monthly but wants <salary*3>
Dream Salary
King earns $24000 monthly but wants $72000
*/
select last_name || ‘ earns ‘||salary||‘ monthly but wants ‘||salary*3 as "A GREAT DREAM" from employees

/*7.    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
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‘)
 ||‘ king    AD_PRES    A‘ as SOMEWORDS from employees

--8.    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 ‘ ‘
                                                end
 ||‘ king    AD_PRES    A‘ as SOMEWORDS from employees