create table dept
(
deptno varchar(10) primary key,
dname varchar(10)
);
create table emp
(
empno varchar(10) primary key,
ename varchar(10),
job varchar(10),
mgr varchar(10),
sal varchar(10),
deptno varchar(10) references dept(deptno)
);
drop table dept;
drop table emp;
insert into dept values ('1','事业部');
insert into dept values ('2','销售部');
insert into dept values ('3','技术部');
insert into emp values ('01','jacky','clerk','tom','1000','1');
insert into emp values ('02','tom','clerk','','2000','1');
insert into emp values ('07','biddy','clerk','','2000','1');
insert into emp values ('03','jenny','sales','pretty','600','2');
insert into emp values ('04','pretty','sales','','800','2');
insert into emp values ('05','buddy','jishu','canndy','1000','3');
insert into emp values ('06','canndy','jishu','','1500','3');
select * from dept;
select * from emp;
1.列出emp表中各部门的部门号，最高工资，最低工资
select e.deptno ,max(sal) ,min(sal) from emp as e group by e.deptno;
解析：各部门 提示：分组查询，所以用group by
2 列出emp表中各部门job为'CLERK'的员工的最低工资，最高工资
select e.deptno ,max(sal) ,min(sal) from emp as e where e.job="CLERK" group by e.deptno;
解析：各部门 提示：分组查询， job提示：条件查询，所以用到 group by 和 where
3 对于emp中最低工资小于2000的部门，列出job为'CLERK'的员工的部门号，最低工资，最高工资
select b.deptno ,max(sal) ,min(sal) from emp as b where b.job="CLERK"
and (select min(sal) from emp as a where a.deptno=b.deptno)<2000 group by b.deptno;
解析：以上面两个题为基础，“emp中最低工资小于2000的部门”只是一个条件而已。
4 据部门号由高而低，工资有低而高列出每个员工的姓名，部门号，工资
select * from emp as b order by b.deptno desc ,b.sal asc;
解析：“部门号由高而低，工资有低”提示：需要排序，所以用到 order by 和 desc asc
5 列出'buddy'所在部门中每个员工的姓名与部门号
select * from emp as b where b.deptno=(select a.deptno from emp as a where a.ename="buddy");
解析：“'buddy'所在部门”提示找出他所在的部门号，所以可以理解“找出所有和buddy在同一部门的所有人”
6 列出每个员工的姓名，工作，部门号，部门名
select ename,job,dept.deptno,dept.dname from emp,dept where emp.deptno=dept.deptno;
7 列出emp中工作为'CLERK'的员工的姓名，工作，部门号，部门名
select ename,job,dept.deptno,dept.dname from emp,dept where emp.deptno=dept.deptno where job="CLERK";
8 对于emp中有管理者的员工，列出姓名，管理者姓名（管理者外键为mgr）
select a.deptno,a.ename ,b.ename from emp as a,emp as b where a.mgr is not null and a.mgr=b.ename;
解析：本句可以理解“一个员工他也是领导，所以emp.ename,emp.mgr 都有值并且有相等的员工”
9 对于dept表中，列出所有部门名，部门号，同时列出各部门工作为'CLERK'的员工名与工作
select a.deptno ,a.dname, b.ename ,b.job from dept as a,emp as b where a.deptno=b.deptno and b.job="clerk";
解析：连表即可
http://blog.csdn.net/shiyuntian_wang/article/details/4636799
建表：
DEPARTMENTS: DEPARTMENT_ID(primary key), DEPARTMENT_NAME, LOCATION
EMPLOYEES: EMPLOYEE_ID(primary key), EMPLOYEE_NAME, EMPLOYEE_JOB, MANAGER, SALARY, DEPARTMENT_ID
- 列出EMPLOYEES表中各部门的部门号，最高工资，最低工资
select max(SALARY) as 最高工资,min(SALARY) as 最低工资,DEPARTMENT_ID from EMPLOYEES group by DEPARTMENT_ID;
- 列出EMPLOYEES表中各部门EMPLOYEE_JOB为'CLERK'的员工的最低工资，最高工资
select max(SALARY) as 最高工资,min(SALARY) as 最低工资,DEPARTMENT_ID as 部门号 from EMPLOYEES where EMPLOYEE_JOB = 'CLERK' group by DEPARTMENT_ID;
- 对于EMPLOYEES中最低工资小于1000的部门，列出EMPLOYEE_JOB为'CLERK'的员工的部门号，最低工资，最高工资
select max(SALARY) as 最高工资,min(SALARY) as 最低工资,DEPARTMENT_ID as 部门号 from EMPLOYEES as b where EMPLOYEE_JOB ='CLERK' and 1000>(select min(SALARY) from EMPLOYEES as a where a.DEPARTMENT_ID = b.DEPARTMENT_ID) group by b.DEPARTMENT_ID
- 根据部门号由高而低，工资有低而高列出每个员工的姓名，部门号，工资
select DEPARTMENT_ID as 部门号,EMPLOYEE_NAME as 姓名,SALARY as 工资 from EMPLOYEES order by DEPARTMENT_ID desc,SALARY asc
- 列出'张三'所在部门中每个员工的姓名与部门号
select EMPLOYEE_NAME,DEPARTMENT_ID from EMPLOYEES where DEPARTMENT_ID = (select DEPARTMENT_ID from EMPLOYEES where EMPLOYEE_NAME = '张三')
- 列出每个员工的姓名，工作，部门号，部门名
select EMPLOYEE_NAME,EMPLOYEE_JOB,EMPLOYEES.DEPARTMENT_ID,DEPARTMENTS.DEPARTMENT_NAME from EMPLOYEES,DEPARTMENTS where EMPLOYEES.DEPARTMENT_ID = DEPARTMENTS.DEPARTMENT_ID
- 列出EMPLOYEES中工作为'CLERK'的员工的姓名，工作，部门号，部门名
select EMPLOYEE_NAME,EMPLOYEE_JOB,DEPARTMENTS.DEPARTMENT_ID,DEPARTMENT_NAME from EMPLOYEES,DEPARTMENTS where DEPARTMENTS.DEPARTMENT_ID = EMPLOYEES.DEPARTMENT_ID and DEPARTMENT_JOB = 'CLERK'
- 对于EMPLOYEES中有管理者的员工，列出姓名，管理者姓名（管理者外键为MANAGER）
select a.EMPLOYEE_NAME as 姓名,b.EMPLOYEE_NAME as 管理者 from EMPLOYEES as a,EMPLOYEES as b where a.MANAGER is not null and a.MANAGER = b.EMPLOYEE_ID
- 对于DEPARTMENTS表中，列出所有部门名，部门号，同时列出各部门工作为'CLERK'的员工名与工作
select DEPARTMENT_NAME as 部门名,DEPARTMENTS.DEPARTMENT_ID as 部门号,EMPLOYEE_NAME as 员工名,EMPLOYEE_JOB as 工作 from DEPARTMENTS,EMPLOYEES where DEPARTMENTS.DEPARTMENT_ID *= EMPLOYEES.DEPARTMENT_ID and EMPLOYEE_JOB = 'CLERK'
- 对于工资高于本部门平均水平的员工，列出部门号，姓名，工资，按部门号排序
select a.DEPARTMENT_ID as 部门号,a.EMPLOYEE_NAME as 姓名,a.SALARY as 工资 from EMPLOYEES as a where a.SALARY>(select avg(SALARY) from EMPLOYEES as b where a.DEPARTMENT_ID = b.DEPARTMENT_ID) order by a.DEPARTMENT_ID
- 对于EMPLOYEES，列出各个部门中平均工资高于本部门平均水平的员工数和部门号，按部门号排序
select count(a.SALARY) as 员工数,a.DEPARTMENT_ID as 部门号 from EMPLOYEES as a where a.SALARY>(select avg(SALARY) from EMPLOYEES as b where a.DEPARTMENT_ID = b.DEPARTMENT_ID) group by a.DEPARTMENT_ID order by a.DEPARTMENT_ID
- 对于EMPLOYEES中工资高于本部门平均水平，人数多与1人的，列出部门号，人数，按部门号排序
select count(a.EMPLOYEE_ID) as 员工数,a.DEPARTMENT_ID as 部门号,avg(SALARY) as 平均工资 from EMPLOYEES as a where (select count(c.EMPLOYEE_ID) from EMPLOYEES as c where c.DEPARTMENT_ID = a.DEPARTMENT_ID and c.SALARY>(select avg(SALARY) from EMPLOYEES as b where c.DEPARTMENT_ID = b.DEPARTMENT_ID))>1 group by a.DEPARTMENT_ID order by a.DEPARTMENT_ID
- 对于EMPLOYEES中低于自己工资至少5人的员工，列出其部门号，姓名，工资，以及工资少于自己的人数
select a.DEPARTMENT_ID,a.EMPLOYEE_NAME,a.SALARY,(select count(b.EMPLOYEE_NAME) from EMPLOYEES as b where b.SALARY < a.SALARY) as 人数 from EMPLOYEES as a where (select count(b.EMPLOYEE_NAME) from EMPLOYEES as b where b.SALARY<a.SALARY)>5