MySQL基础06 - 34道练习题

/*
27.列出所有员工的姓名、部门名称和工资。
select 
	e.ename,d.dname,e.sal 
from  
	emp e 
join 
	dept d 
on 
	e.deptno = d.deptno;
+--------+------------+---------+
| ename  | dname      | sal     |
+--------+------------+---------+
| CLARK  | ACCOUNTING | 2450.00 |
| KING   | ACCOUNTING | 5000.00 |
| MILLER | ACCOUNTING | 1300.00 |
| SMITH  | RESEARCH   |  800.00 |
| JONES  | RESEARCH   | 2975.00 |
| SCOTT  | RESEARCH   | 3000.00 |
| ADAMS  | RESEARCH   | 1100.00 |
| FORD   | RESEARCH   | 3000.00 |
| ALLEN  | SALES      | 1600.00 |
| WARD   | SALES      | 1250.00 |
| MARTIN | SALES      | 1250.00 |
| BLAKE  | SALES      | 2850.00 |
| TURNER | SALES      | 1500.00 |
| JAMES  | SALES      |  950.00 |
+--------+------------+---------+

28.列出所有部门的详细信息和人数
select 
	d.*,count(e.ename) 
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) |
+--------+------------+----------+----------------+
|     40 | OPERATIONS | BOSTON   |              0 |
|     10 | ACCOUNTING | NEW YORK |              3 |
|     20 | RESEARCH   | DALLAS   |              5 |
|     30 | SALES      | CHICAGO  |              6 |
+--------+------------+----------+----------------+

29.列出各种工作的最低工资及从事此工作的雇员姓名。

select 
	job,min(sal) minsal 
from 
	emp 
group by 
	job;
+-----------+----------+
| job       | minsal   |
+-----------+----------+
| ANALYST   |  3000.00 |
| CLERK     |   800.00 |
| MANAGER   |  2450.00 |
| PRESIDENT |  5000.00 |
| SALESMAN  |  1250.00 |
+-----------+----------+

// 将以上表看成t表,emp表和t表进行表连接
select 
	e.ename,t.* 
from 
	emp e 
join
	(select job,min(sal) minsal from emp group by job) t 
on 
	e.job = t.job and e.sal = t.minsal;
+--------+-----------+---------+
| ename  | job       | minsal  |
+--------+-----------+---------+
| SMITH  | CLERK     |  800.00 |
| WARD   | SALESMAN  | 1250.00 |
| MARTIN | SALESMAN  | 1250.00 |
| CLARK  | MANAGER   | 2450.00 |
| SCOTT  | ANALYST   | 3000.00 |
| KING   | PRESIDENT | 5000.00 |
| FORD   | ANALYST   | 3000.00 |
+--------+-----------+---------+

30.列出各个部门的MANAGER（领导）的最低薪金
select 
	deptno,min(sal) minsal   
from 
	emp 
where 
	job = 'MANAGER' 
group by 
	deptno;
+--------+---------+
| deptno | minsal  |
+--------+---------+
|     10 | 2450.00 |
|     20 | 2975.00 |
|     30 | 2850.00 |
+--------+---------+

31.列出所有员工的年工资，按年薪从低到高排序。
select 
	ename,(sal + ifnull(comm,0))*12 as yearsal 
from 
	emp  
order by 
	yearsal asc;
	
32.求出员工领导的薪水超过3000的员工名称与领导名称。
select 
	e1.ename '员工',e2.ename '领导',e2.sal 
from 
	emp e1 
join 
	emp e2 
on 
	e1.mgr = e2.empno 
where 
	e2.sal > 3000;
+-------+------+---------+
| 员工   | 领导  | sal    |
+-------+------+---------+
| JONES | KING | 5000.00 |
| BLAKE | KING | 5000.00 |
| CLARK | KING | 5000.00 |
+-------+------+---------+

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。
// 加where条件，不要加having，效率更高
select d.dname,d.deptno,sum(ifnull(e.sal,0)),count(e.ename)  
from 
	emp e 
right join 	
	dept d 
on 
	e.deptno = d.deptno 
where 
	d.dname like '%S%' 
group by 
	d.deptno,d.dname,d.loc;
+------------+--------+----------------------+----------------+
| dname      | deptno | sum(ifnull(e.sal,0)) | count(e.ename) |
+------------+--------+----------------------+----------------+
| RESEARCH   |     20 |             10875.00 |              5 |
| SALES      |     30 |              9400.00 |              6 |
| OPERATIONS |     40 |                 0.00 |              0 |
+------------+--------+----------------------+----------------+

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;
mysql> select * from emp;
+-------+--------+-----------+------+------------+---------+---------+--------+
| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO |
+-------+--------+-----------+------+------------+---------+---------+--------+
|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  880.00 |    NULL |     20 |
|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1760.00 |  300.00 |     30 |
|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1375.00 |  500.00 |     30 |
|  7566 | JONES  | MANAGER   | 7839 | 1981-04-02 | 3272.50 |    NULL |     20 |
|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1375.00 | 1400.00 |     30 |
|  7698 | BLAKE  | MANAGER   | 7839 | 1981-05-01 | 3135.00 |    NULL |     30 |
|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2695.00 |    NULL |     10 |
|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3300.00 |    NULL |     20 |
|  7839 | KING   | PRESIDENT | NULL | 1981-11-17 | 5500.00 |    NULL |     10 |
|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1650.00 |    0.00 |     30 |
|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1210.00 |    NULL |     20 |
|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 | 1045.00 |    NULL |     30 |
|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3300.00 |    NULL |     20 |
|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1430.00 |    NULL |     10 |
+-------+--------+-----------+------+------------+---------+---------+--------+


*/