这篇文章的基表是大家最为熟知的Scott用户下的emp员工表,dept部门表以及salgrade薪水等级表,一切的语句都是围绕它写的。
下面来看一下Oracle中常用的操作都有哪些吧!
一、用户的有关操作
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创建用户
create user scott identified by 123456;
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给用户分配权限
grant connect,resource to scott; grant create view to scott; grant create synonym to scott;
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撤销用户权限
revoke connect,resource from scott; revoke create view from scott; revoke create synonym from scott;
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删除用户
drop user scott cascade;
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修改用户密码
alter user scott identified by 123456;--命令修改 conn scott/123456 password;--命令可视化修改1 connect scott/123456 password;--命令可视化修改2
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设置用户是否锁定
alter user scott account lock; alter user scott account unlock;
二、表空间的有关操作
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创建表空间
create tablespace mysapce datafile 'D:a.ora' size 10M--绝对路径和大小 extent management local uniform size 1M;--每个分区的大小
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扩展表空间
alter tablespace mysapce add datafile 'D:b.ora' size 10M;
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为ORACLE对象指定表空间
create user space_text identified by 123456 account unlock default tablespace mysapce; --创建表、索引也可以指定表空间;一旦指定,表空间无法修改。
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删除表空间
drop tablespace mysapce;
三、DDL的有关操作
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表table
--创建员工表
CREATE TABLE EMP( EMPNO NUMBER(4) CONSTRAINT PK_EMP PRIMARY KEY, ENAME VARCHAR2(10), JOB VARCHAR2(9), MGR VARCHAR(10), --上司 HIREDATE DATE, --入职日期 SAL NUMBER(7,2), --薪水 COMM NUMBER(7,2), --津贴 DEPTNO NUMBER(2) CONSTRAINT FK_DEPTNO REFERENCES DEPT );
--创建部门表
CREATE TABLE DEPT( DEPTNO NUMBER(2) CONSTRAINT PK_DEPT PRIMARY KEY, DNAME VARCHAR2(14) , LOC VARCHAR2(13) --地址 );
--创建工资等级表
CREATE TABLE SALGRADE( GRADE NUMBER, --等级 LOSAL NUMBER, --等级中最低的薪水 HISAL NUMBER --等级中最高的薪水 );
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视图view
--为emp表的empno,ename,sal和dept表的dname和salgrade表的grade创建一个视图
create view emp_dept_salgrade as select e.empno,e.ename,e.sal,d.dname,s.grade from emp e inner join dept d using(deptno) inner join salgrade s on e.sal between s.losal and s.hisal; select * from emp_dept_salgrade;--通过视图查询
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序列sequence
--为员工表的EMPNO创建一个序列
create sequence emp_empno_seq start with 1001 increment by 1 nomaxvalue nocycle cache 10; select emp_empno_seq.currval from dual;--查询序列的当前值 select emp_empno_seq.nextval from dual;--查询序列的下一个值
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同义词synonym
--为视图emp_dept_salgrade创建同义词
create synonym eds for emp_dept_salgrade; select * from eds;--通过视图的同义词来查询视图中的数据
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触发器trigger
--为员工表的empno创建一个自动插入的触发器
create or replace trigger emp_empno_tri before insert on emp for each row begin :new.empno:=emp_empno_seq.nextval;--语句级(for each row)触发器里面可以:new.列名来给进行操作。 end;
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存储过程procedure
--创建一个可以控制行数的乘法表的过程。
create or replace procedure nine_nine(nine_line in number) as begin for i in 1..nine_line loop for j in 1..i loop dbms_output.put(i||'*'||j||'='||i*j||' '); end loop; dbms_output.put_line(''); end loop; end;
--调用这个乘法过程
set serveroutput on; execute nine_nine(9);
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存储函数function
--创建一个求1!+2!+..+20!的值的存储函数
create or replace function one_tw return number as value_sum number:=0; value_loop number:=1; begin for i in 1..20 loop value_loop:=value_loop*i; value_sum:=value_sum+value_loop; end loop; return value_sum; end; select one_tw() from dual;--调用函数 <span style="color: #008000;">备注:存储函数的调用可以放在表达式的位置,即表达式在哪里成立,它就可以在哪里调用。</span>
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事务rollback、commit、savepoint
三、常用的结构查询
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查询用户和用户的信息
select username,user_id,password,default_tablespace from dba_users; select * from dba_users;
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查询用户所拥有的角色
select * from user_role_privs;--系统用户 select * from session_roles;--普通用户
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查询用户的权限
select * from user_sys_privs;--普通用户和系统用户都可以查看表中列的字符长度和字节长度 select length(ename),lengthb(ename) from emp;
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查询表的相关信息
SELECT table_name, tablespace_name, temporary FROM user_tables;
查询表中列的相关信息
SELECT table_name,column_name, data_type, data_length, data_precision, data_scale FROM user_tab_columns;
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对表进行重命名
rename student to mystudent;
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给表添加备注
comment on table student is '我的练习';
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给表中列添加备注
comment on column student.sno is '学生号';
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查看表和视图的备注信息
select * from user_tab_comments where table_name='STUDENT';
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查看表和视图中列的备注信息
select * from user_col_comments where table_name='STUDENT';
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查看表的结构
describe student;
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截断表
truncate table student;
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使用连接运算符
select empno||ename as employees from emp; select concat(empno,ename) as employees from emp;
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查看表的约束信息
select * from user_constraints where table_name='EMP';
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查看列的约束信息
select * from user_cons_columns where column_name='SNO';
查看序列的信息
select * from user_sequences where sequence_name='EMP_EMPNO_SEQ';
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查看索引的信息
select * from user_indexes;
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查看视图的信息
select * from user_views;
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查看同义词
select * from user_synonyms;
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查看触发器
select * from user_triggers;
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查看存储过程
select * from user_procedures;
四、DML的有关操作
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插入数据insert
--dept-- INSERT INTO DEPT select 10,'ACCOUNTING','NEW YORK' from dual union select 20,'RESEARCH','DALLAS' from dual union select 30,'SALES','CHICAGO' from dual union select 40,'OPERATIONS','BOSTON' from dual; commit; <span style="font-family: 'Helvetica Neue', Helvetica, 'Hiragino Sans GB', 'Microsoft YaHei', Arial, sans-serif; line-height: 25.6px;">--使用Oracle中的多行插入方法,关键字union,select自己想要的数据,与dual伪表组建一个完整的结构。</span>
--emp-- INSERT INTO EMP(ename,job,mgr,hiredate,sal,comm,deptno) select 'SMITH','CLERK',1009,to_date('17-12-1980','dd-mm-yyyy'),800,NULL,20 from dual union select 'ALLEN','SALESMAN',1006,to_date('20-2-1981','dd-mm-yyyy'),1600,300,30 from dual union select 'WARD','SALESMAN',1006,to_date('22-2-1981','dd-mm-yyyy'),1250,500,30 from dual union select 'JONES','MANAGER',1009,to_date('2-4-1981','dd-mm-yyyy'),2975,NULL,20 from dual union select 'MARTIN','SALESMAN',1006,to_date('28-9-1981','dd-mm-yyyy'),1250,1400,30 from dual union select 'BLAKE','MANAGER',1009,to_date('1-5-1981','dd-mm-yyyy'),2850,NULL,30 from dual union select 'CLARK','MANAGER',1009,to_date('9-6-1981','dd-mm-yyyy'),2450,NULL,10 from dual union select 'SCOTT','ANALYST',1004,to_date('13-10-87','dd-mm-rr')-85,3000,NULL,20 from dual union select 'KING','PRESIDENT',1007,to_date('17-11-1981','dd-mm-yyyy'),5000,NULL,10 from dual union select 'TURNER','SALESMAN',1006,to_date('8-9-1981','dd-mm-yyyy'),1500,0,30 from dual union select 'ADAMS','CLERK',1009,to_date('13-10-87', 'dd-mm-rr')-51,1100,NULL,20 from dual union select 'JAMES','CLERK',1009,to_date('3-12-1981','dd-mm-yyyy'),950,NULL,30 from dual union select 'FORD','ANALYST',1004,to_date('3-12-1981','dd-mm-yyyy'),3000,NULL,20 from dual union select 'MILLER','CLERK',1004,to_date('23-1-1982','dd-mm-yyyy'),1300,NULL,10 from dual; commit;--这里使用了触发器emp_empno_tri来自动插入emp表的empno员工编号 --salgrade-- INSERT INTO SALGRADE VALUES (1,700,1200); INSERT INTO SALGRADE VALUES (2,1200,1400); INSERT INTO SALGRADE VALUES (3,1400,2000); INSERT INTO SALGRADE VALUES (4,2000,3000); INSERT INTO SALGRADE VALUES (5,3000,9999); commit;
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更新数据update
update emp set sal=3000 where empno=1004;
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删除数据delete
delete from emp where empno=1004;--from可以省略
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查询数据select
查询数据是DML语句中最关键的部分,也是最难的部分,在这里有许多围绕scott用户的实例,都是稍微复杂一点的查询,简单的就没必要写了。
1、最常用
select * from emp; select * from dept; select * from salgrade;
2、内部连接
2-1.查询每个员工所在的部门,使用where连接.
select e.empno,e.ename,d.dname from emp e,dept d where e.deptno=d.deptno;
2-2.inner join on连接.
select e.empno,e.ename,d.dname from emp e inner join dept d on e.deptno=d.deptno;
2-3.inner join using连接.
select e.empno,e.ename,d.dname from emp e inner join dept d using(deptno);
3、外部连接
3-1.左外连接:例如:查询出部门的员工的情况(显示所有部门).
select e.ename,d.dname from emp e left join dept d using(deptno);
3-2.右外连接用(+).
select e.ename,d.dname from emp e,dept d where e.deptno=d.deptno(+);
3-3.右外连接:例如:查询出所有的员工的部门情况(显示了所有员工).
select e.ename,d.dname from emp e right join dept d using(deptno);
3-4.右外连接用(+).
select e.ename,d.dname from emp e,dept d where e.deptno(+)=d.deptno;
4、自连接
4-1.查询出员工及他的上级。
select a.ename as 员工,b.ename as 上级 from emp a ,emp b where a.mgr=b.empno; select a.ename as 上级,b.ename as 上级 from emp a inner join emp b on a.mgr=b.empno;
5、子查询
5-1.查询工资高于平均工资的员工信息.
select * from emp where sal>(select avg(sal) from emp);
5-2.使用ANY查询任意满足工资低于最低档工资的员工信息.
select * from emp where sal<any(select losal from salgrade);
5-3.查询所有员工所属部门.
select dname from (select distinct dname from dept);
5-4.查询满足大于每个部门的最低工资的员工信息.
select * from emp where sal>all(select min(sal) from emp group by deptno);
5-5.查询出每个部门中,高出本部门平均工资的员工的雇员号和姓名.
select empno as 雇员号,ename as 姓名 from emp outer where sal> (select avg(sal) from emp inner where inner.deptno=outer.deptno );
5-6.查询不在部门10的员工信息:注意子查询中的1,由于只关心子查询是否返回TRUE值,使用1可以提高查询的效率.
5-6.1.EXISTS子查询效率高于IN子查询.
select * from emp a where not exists (select 1 from emp b where a.deptno=10);
5-6.2.in的效率低,但比较好理解.
select * from emp where deptno not in 10;
5-7.查询emp表中可以管理别的员工的员工.
select ename from emp a where exists(select ename from emp b where a.empno=b.mgr);
5-8.删除中部门重复行.
delete emp where rowid not in (select min(rowid) from emp group by deptno);
5-9.查找emp表第6-10条记录.
select * from(select rownum m,ename,sal,deptno from emp where rownum<=10)
where m>5;
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