查询语句 34道练习题

20。列出最低薪资大于1500的各种工作 以及从事此工作的全部雇员人数按照工作岗位求最小值

按照工作岗位找到工资大于1500的

select job from emp group by job having min(sal)>1500;
+-----------+
| job       |
+-----------+
| ANALYST   |
| MANAGER   |
| PRESIDENT |
+-----------+
找总人数
select job from emp group by job having min(sal)>1500;

+-----------+----------+
| job       | count(*) |
+-----------+----------+
| ANALYST   |        2 |
| MANAGER   |        3 |
| PRESIDENT |        1 |
+-----------+----------+
按照岗位找人

select 
 e.* 
 from
 emp e
 join
 (select job from emp group by job having min(sal)>1500) t
 on
 t.job=e.job;
+-------+-------+-----------+------+------------+---------+------+--------+
| EMPNO | ENAME | JOB       | MGR  | HIREDATE   | SAL     | COMM | DEPTNO |
+-------+-------+-----------+------+------------+---------+------+--------+
|  7566 | JONES | MANAGER   | 7839 | 1981-04-02 | 2975.00 | NULL |     20 |
|  7698 | BLAKE | MANAGER   | 7839 | 1981-05-01 | 2850.00 | NULL |     30 |
|  7782 | CLARK | MANAGER   | 7839 | 1981-06-09 | 2450.00 | NULL |     10 |
|  7788 | SCOTT | ANALYST   | 7566 | 1987-04-19 | 3000.00 | NULL |     20 |
|  7839 | KING  | PRESIDENT | NULL | 1981-11-17 | 5000.00 | NULL |     10 |
|  7902 | FORD  | ANALYST   | 7566 | 1981-12-03 | 3000.00 | NULL |     20 |
+-------+-------+-----------+------+------------+---------+------+--------+

21.找出部门sales的员工姓名 假设不知道部门编号

找部门编号 

select deptno from dept where dname='sales';
+--------+
| deptno |
+--------+
|     30 |
+--------+

找员工：
select ename from emp where deptno=(select deptno from dept where dname='sales');

+--------+
| ename  |
+--------+
| ALLEN  |
| WARD   |
| MARTIN |
| BLAKE  |
| TURNER |
| JAMES  |
+--------+

22.列出薪资高于公司平均薪资的所有员工 所在部门，上级领导，工资等级

 找出工资高于平均值的
select 
	e.ename '员工', d.dname,l.ename '领导', s.grade
from   先是 员工和岗位匹配  找到对应的岗位
 	emp e
join 
	dept d
on
	e.deptno=d.deptno
left join  表左自连接找到对应的领导
	emp l
on
 	e.mgr=l.empno
join      找到每一个员工对应的工资等级
	salgrade s
on
	e.sal between s.losal and s.hisal
where      工资的等级大于平均工资
	e.sal>(select avg(sal) from emp);
	
+-------+------------+-------+-------+
| 员工     | dname   | 领导   | grade |
+-------+------------+-------+-------+
| JONES | RESEARCH   | KING  |     4 |
| BLAKE | SALES      | KING  |     4 |
| CLARK | ACCOUNTING | KING  |     4 |
| SCOTT | RESEARCH   | JONES |     4 |
| KING  | ACCOUNTING | NULL  |     5 |
| FORD  | RESEARCH   | JONES |     4 |
+-------+------------+-------+-------+

23.列出与scott从事相同工作的所有员工以及部门名称

找到scott是干嘛的
select job from emp where ename='scott';
找与scott相同岗位的名称 部门编号 
select e.ename, e.job, d.dname from emp  e 

join
dept d
on 
d.deptno=e.deptno

where job=(select job from emp where ename='scott');
+-------+---------+----------+
| ename | job     | dname    |
+-------+---------+----------+
| SCOTT | ANALYST | RESEARCH |
| FORD  | ANALYST | RESEARCH |
+-------+---------+----------+

24.列出薪资等于部门30 中员工的薪金的其他员工的姓名和薪资

部门30的薪资：
select  distinct sal from emp where deptno=30; 

+---------+
| sal     |
+---------+
| 1600.00 |
| 1250.00 |
| 2850.00 |
| 1500.00 |
|  950.00 |
+---------+
找其他部门与这个薪资相同的员工


select ename sal from emp where sal in (select  distinct sal from emp where deptno=30) and deptno<>30;


Empty set (0.00 sec)

25.列出薪资高于在部门30中工作的所有员工的薪资的员工姓名和薪资部门名称

就是找出部门30的最高薪资
select 
e.ename, e.sal, d.dname
from
 emp e
join 
dept d
on 
e.deptno=d.deptno
where
e.sal>(select max(sal) from emp where deptno=30);


+-------+---------+------------+
| ename | sal     | dname      |
+-------+---------+------------+
| KING  | 5000.00 | ACCOUNTING |
| JONES | 2975.00 | RESEARCH   |
| SCOTT | 3000.00 | RESEARCH   |
| FORD  | 3000.00 | RESEARCH   |
+-------+---------+------------+

26.列出在每个部门工作的员工数量，平均工资和平均服务期限

 mysql中 有专门计算日期差的函数 timestampdiff(间隔类型，起始日期，当前日期)
 
 
 select
     d.*, count(e.ename), ifnull(avg(e.sal),0), ifnull(avg(timestampdiff(year,hiredate,now())),0) as '平均年'
     from
     emp e
     right join
     dept d
     on
     e.deptno=d.deptno
     group by
     d.deptno, d.dname, d.loc;
     
     
     +--------+------------+----------+----------------+----------------------+---------+
| DEPTNO | DNAME      | LOC      | count(e.ename) | ifnull(avg(e.sal),0) | 平均年       |
+--------+------------+----------+----------------+----------------------+---------+
|     10 | ACCOUNTING | NEW YORK |              3 |          2916.666667 | 38.3333 |
|     20 | RESEARCH   | DALLAS   |              5 |          2175.000000 | 36.4000 |
|     30 | SALES      | CHICAGO  |              6 |          1566.666667 | 38.5000 |
|     40 | OPERATIONS | BOSTON   |              0 |             0.000000 |  0.0000 |
+--------+------------+----------+----------------+----------------------+---------+

27.列出所有员工的姓名 部门和工资

select
	e.ename, e.sal, d.dname 
from 
	emp e  
join 
	dept d 
on 
	e.deptno= d.deptno;
	
	+--------+---------+------------+
| ename  | sal     | dname      |
+--------+---------+------------+
| CLARK  | 2450.00 | ACCOUNTING |
| KING   | 5000.00 | ACCOUNTING |
| MILLER | 1300.00 | ACCOUNTING |
| SMITH  |  800.00 | RESEARCH   |
| JONES  | 2975.00 | RESEARCH   |
| SCOTT  | 3000.00 | RESEARCH   |
| ADAMS  | 1100.00 | RESEARCH   |
| FORD   | 3000.00 | RESEARCH   |
| ALLEN  | 1600.00 | SALES      |
| WARD   | 1250.00 | SALES      |
| MARTIN | 1250.00 | SALES      |
| BLAKE  | 2850.00 | SALES      |
| TURNER | 1500.00 | SALES      |
| JAMES  |  950.00 | SALES      |
+--------+---------+------------+

28.列出所有部门的详细信息和人数

select 
	d.dname, d.deptno, d.loc, count(e.ename)
from 
	emp e
left join 
	dept d
on 
	d.deptno=e.deptno
group by 
	d.dname;
+------------+--------+----------+----------------+
| dname      | deptno | loc      | count(e.ename) |
+------------+--------+----------+----------------+
| ACCOUNTING |     10 | NEW YORK |              3 |
| RESEARCH   |     20 | DALLAS   |              5 |
| SALES      |     30 | CHICAGO  |              6 |
+------------+--------+----------+----------------+

29.找出每个工作的最低工资 以及从事此工作的雇员姓名

select job, ename, min(sal) from emp group by job;

+-----------+-------+----------+
| job       | ename | min(sal) |
+-----------+-------+----------+
| ANALYST   | SCOTT |  3000.00 |
| CLERK     | SMITH |   800.00 |
| MANAGER   | JONES |  2450.00 |
| PRESIDENT | KING  |  5000.00 |
| SALESMAN  | ALLEN |  1250.00 |
+-----------+-------+----------+

30.列出各个部门的领导的最低薪资

select
deptno, min(sal)
from emp 
where job='manager'
group by deptno;
+--------+----------+
| deptno | min(sal) |
+--------+----------+
|     10 |  2450.00 |
|     20 |  2975.00 |
|     30 |  2850.00 |
+--------+----------+

31.列出所有员工的年薪 按照从低到高排序

select ename, (sal*12)+ifnull(comm,0) a from emp order by a ;
+--------+----------+
| ename  | a        |
+--------+----------+
| SMITH  |  9600.00 |
| JAMES  | 11400.00 |
| ADAMS  | 13200.00 |
| WARD   | 15500.00 |
| MILLER | 15600.00 |
| MARTIN | 16400.00 |
| TURNER | 18000.00 |
| ALLEN  | 19500.00 |
| CLARK  | 29400.00 |
| BLAKE  | 34200.00 |
| JONES  | 35700.00 |
| FORD   | 36000.00 |
| SCOTT  | 36000.00 |
| KING   | 60000.00 |
+--------+----------+

32 找出员工领导的薪水超过3000的员工与领导名称

自连接
select 
	a.ename, b.ename
from
     emp a
join
	emp b
on 
	a.mgr=b.empno
where
	b.sal>3000;
+-------+-------+
| ename | ename |
+-------+-------+
| JONES | KING  |
| BLAKE | KING  |
| CLARK | KING  |
+-------+-------+

33.求出部门名称中，带‘s’字符的部门员工的工资合计。部门人数

select
d.deptno, d.dname, d.loc, count(e.ename), sum(e.sal)
from
emp e
right join 
dept d
on
e.deptno = d.deptno
where 
d.dname like'%s%'
group by
d.deptno;

+--------+------------+---------+----------------+------------+
| deptno | dname      | loc     | count(e.ename) | sum(e.sal) |
+--------+------------+---------+----------------+------------+
|     20 | RESEARCH   | DALLAS  |              5 |   10875.00 |
|     30 | SALES      | CHICAGO |              6 |    9400.00 |
|     40 | OPERATIONS | BOSTON  |              0 |       NULL |
+--------+------------+---------+----------------+------------+

34.给任职日期超过30年的员工加薪10%

update emp set sal=sal*1.1 where timestampdiff(year,hiredate,now())>30;