1.为表vendor_master创建一个视图，该视图将VENADD1、VENADD2和VENADD3(地址的三部分，都为varchar2性) 3个列连接起来组成名为VENADDRES的列.
create view venadds as
select venadd1 from vendor_master union all
select venadd2 from vendor_master union all
select venadd3 from vendor_master;
grant create any view to scott;
create view emp_master as
select empno from emp union all
select deptno from emp;
select * from emp_master order by empno;
CREATE VIEW 视图名称 AS
SELECT * FROM 第1张表 UNION ALL
SELECT * FROM 第2张表 UNION ALL
SELECT * FROM 第3张表;
2.创建名为“my_seq”的序列,该序列的起始值为1000,并在每次查询时增加10,直到该序列达到1100,然后重新从1000开始.
CREATE SEQUENCE my_seq
START WITH 1000
INCREMENT BY 10
MAXVALUE 1100
MINVALUE 1000
CYCLE
CACHE 10;
SELECT my_seq.NEXTVAL FROM emp;
SELECT my_seq.CURRVAL FROM emp;
DROP SEQUENCE my_seq;
3.在表order_detail表的orderno和itemcode列上创建一个唯一组合索引.
create unique index x_order_detail
ON order_detail(orderno, itemcode);
CREATE UNIQUE INDEX x_emp
ON emp(ename, empno);
drop INDEX x_emp;
二、使用如下表
dept部门表(deptno部门编号/dname部门名称/loc地点)
完成以下查询
--1、列出月薪比 "BLAKE" 少的所有雇员
select ename, sal from emp where sal < (select sal from emp where upper(ename)='BLAKE');
--2、列出至少有一个雇员的部门详细信息
select distinct deptno,dname,loc from dept where deptno in (select distinct deptno from emp);
--3、列出所有雇员的姓名及其直接上级的姓名。
select a.ename, b.ename mgrname from emp a,emp b where a.mgr = b.empno;
--4、列出入职日期早于其直接上级的所有雇员
select e.ename from emp e ,emp d where e.mgr=d.empno and e.hiredate < d.hiredate;
--5、列出没有雇员的部门信息
select distinct dname ,deptno,loc from dept where deptno not in (select distinct deptno from emp);
--6、列出所有“CLERK”（办事员）的姓名及其部门名称
select ename,dname from emp ,dept where emp.deptno = dept.deptno and emp.job=upper('clerk');
--7、列出最低薪金大于1500的工作类别信息
select job ,min(sal) from emp group by job having min(sal) > 1500;
--8、列出月薪高于公司平均水平的所有雇员
select ename from emp where (sal+nvl(comm,0)) > (select avg(sal+nvl(comm,0)) from emp);
--9、列出与“SCOTT”从事相同工作的所有雇员
select ename, job from emp where job in (select job from emp where upper(ename) = 'SCOTT');
--10、列出某些雇员的姓名和薪金，条件是他们的月薪高于部门30中所有雇员的薪金
select ename, sal from emp where sal > (select max(sal) from emp where deptno = 30);
--11、列出每个部门的信息以及该部门中雇员的数量--
select dept.deptno,dname,loc,count(ename) num
from emp,dept where emp.deptno = dept.deptno
group by dept.deptno,dname,loc;
--12、列出所有雇员的雇员名称、部门名称和月薪
select ename,sal+nvl(comm,0) salary ,dname from emp left join dept on emp.deptno = dept.deptno;
--13、列出各个部门的MANAGER（经理）的最低薪金
select dname,min(sal) from emp e join dept d on e.job='MANAGER' and e.deptno = d.deptno group by dname;
--14、列出所有雇员的年薪，并且按年薪排序
select ename ,(sal+nvl(comm,0))*12 salary from emp order by salary;
--15、列出薪金水平处于第四位到第七位的雇员
Select * from (Select ename,sal, rank() over (order by sal desc) as grade from emp) where grade between 4 and 7;