SQL数据表示例

关于SQL数据表的实例

示例:

查找emp表

select * from emp;

查找emp表的sal

select a.SAL from emp a;

查找emp表的ename

select a.ename from emp a;

emp表的sal*10

select a.SAL*10 from emp a;

emp表的sal的平均值

select avg(a.sal) from emp a;

emp表的sal的总和

select sum(a.sal) from emp a;

emp表的sal的max

select max(a.sal) from emp a;

emp表的sal的min

select min(a.sal) from emp a;

emp表中sal<1000的信息

select * from emp where sal<1000;

ename中含有A的信息

select ename  from emp where ename like'%A%';

emp中ename不含有A的信息

select * from emp where ename not like'%A%';

查询系统时间

select sysdate from dual;

计算薪资小于5000的员工的工资总和

select sum(sal) from emp where sal<5000 ;

计算工资不高于平均工资的工资总和

select sum(sal) from emp where sal<(select avg(sal) from emp);

计算工资小于4000的员工的平均工资

select avg((select sum(sal) from emp where sal<4000)) from emp;

查询薪水低于100000的员工姓名和sal

select ename,sal from emp where  sal<100000;

计算20号部门的员工的最高工资和最低工资

select max(sal),min(sal) from emp where deptno=20;

查询工资大于1000，并且是20号部门的员工的全部信息

select * from emp where sal>1000 and deptno=20;

求最高工资的员工的员工姓名和部门名称

select ename,deptno,sal from emp where sal=(select max(sal) from emp);

将员工薪水小于5000且部门平均薪水大于1000的部门标号列出，按部门平均薪水降序排序

select deptno from emp where sal<5000  group by deptno having avg(sal) >1000;

select sal from emp order by sal desc;

Order by *** desc

查找表emp

select * from emp ;

根据用户名“Smiths”查找他所在的部门

select deptno from emp where ename='SMITH';

查询每个部门的最高工资的人员名称

select e.ename,e.deptno,e.sal from (select deptno as did ,max(sal) as m from emp group by deptno )  s,emp e,dept d where e.sal=s.m and s.did=e.deptno and d.deptno=e.deptno;

查询“Jones”之后第一个进入公司的人

select * from emp where hiredate=(select min(hiredate) from emp where hiredate>(select hiredate from emp where ename='JONES')) ;

查找工资最高的部门名称和工资最低的部门名称及工资

select d.dname,e.sal from emp e,dept d where e.deptno=d.deptno and sal=(select max(m) from (select deptno,max(sal) as m from emp e group by deptno) s)

union

select d.dname,e.sal from emp e,dept d where e.deptno=d.deptno and sal=(select min(m) from (select deptno,min(sal) as m from emp e group by deptno) s)

创建表

create table student(

       StudentId number (6),--学号

       LoginPwd varchar(20),--密码

       StudentName varchar(50),--姓名

       Sex char(2),--性别

       Gradeld Number(6),--所在年级

       Phone number(15),--联系电话

       Address varchar2(255),--现住址

       BornDate Date,--出生日期

       Emile varchar2(50)--电子邮件

);

添加数据

insert into student values(1001,'123456','赵六','男',1507,120,'北京','23-5月-1995','@10422');

insert into student values(1002,'123456','王五','女',1507,110,'北京','23-5月-1995','@10422');

insert into student values(1003,'123456','张三','男',1507,120,'北京','23-5月-1995','@10422');

insert into student values(1004,'123456','李四','女',1507,110,'北京','23-5月-1995','@10422');

提交

commit;

查询此表

select * from student;

根据条件修改

update student set studentname='孙七',loginpwd='666666' where studentid=1001;

select * from student;

根据条件删除

delete from student where studentid=1002;

select * from student;

增加字段

ALTER TABLE 表名称 ADD(列名称 数据类型 [DEFAULT 默认值],列名称 数据类型 [DEFAULT 默认值],…)

删除此表

drop table student;

B卷 创建表空间

create tablespace mytestspace datafile 'e:week3.dbf' size 2M;

创建用户

create user zhangsan identified by zhangsan default tablespace mytestspace

temporary tablespace temp;

创建角色并授权

create role fang;

grant create table to fang;

grant fang to zhangsan;

grant dba to zhangsan;

创建表

create table teacher (

tid number primary key,

tname varchar2(50),

tdate date,

address varchar2(100)

);

select * from teacher;

创建序列

create sequence teachers_sequence minvalue 1 maxvalue 100 (最小值，最大值)cycle (循环)increment by 1(步长值) start with 1（从1开始）;

insert into teacher values(teachers_sequence.nextval,'小李','01-1月-1999','北京');

insert into teacher values(teachers_sequence.nextval,'小张',to_date('1982-1-1','yyyy-mm-dd'),'北京');