- 创建表空间和用户
/*创建临时表空间*/
create temporary tablespace user_temp
tempfile 'E:appfanyongoradataorcl'
size 50m
autoextend on
next 50m maxsize 20480m
extent management local;
/*创建数据表空间*/
create tablespace user_data
logging
datafile 'E:appfanyongoradataorcl'
size 50m
autoextend on
next 50m maxsize 20480m
extent management local;
/*创建用户guest密码为123123*/
create user guest identified by 123456
default tablespace user_data
temporary tablespace user_temp;
- 给用户赋予或收回系统权限
grant create session，create table to guest (with admin option)(系统权限传递)
revoke connect,resource from guest
| 系统权限 | 作用 |
|---|---|
| connect | 连接到数据库 |
| resource | 创建实体 |
| dba | 创建数据库结构 |
- 修改用户口令或删除用户(只有在用户包含数据库时，加上cascade)
alter user guest identified by 123123 /*修改用户guest密码为123123*/
drop user guest[cascade]
- 创建或删除学生表
create table student_fanyong(
stuno number(6) primary key,/*学号*/
name varchar2(10) not null,/*姓名*/
sex char(2) check(sex='男' or sex= '女'),/*性别*/
age number(3),/*年龄*/
birth_date date/*出生日期*/);
drop table student_fanyong;
- 创建和删除视图
create or replace view stu_view(stuno,name,age) as
select stuno,name,age from student_fanyong;
drop view stu_view;
- 创建和删除索引
/*在查询student_fanyong表时优先搜索索引*/
create unique index student_fanyong_name on student_fanyong(name);
- 三种方式的插入操作
/*直接赋值的插入*/
insert into student_fanyong(stuno,name,sex,age,birth_date)
values(121334,'李四','男',21,to_date('10/8/95','mm/dd/yy'));
/*带参数的插入*/
insert into student_fanyong(stuno,name,sex) values(&stuno,'&name','&sex');
/*带子查询的插入*/
insert into student(stuno,name ,sex) select stuno,name,sex from student_fanyong;
- 修改操作
update student_fanyong set name='王五' where name='李四';
- 删除操作
delete from student_fanyong where name='王五';
- 单表查询
/*条件查询*/
select stuno,name from student_fanyong where sex='女';
/*排序显示查询结果*/
select * from student_fanyong order by stuno asc;
/*分组查询，注意select后属性与group by保持一致。属性越靠后，排序比重越大（1,10,100,1000）*/
select stuno,name,sex from student_fanyong group by stuno,name,sex;
/*带条件的分组查询*/
select name ,sex,count(*) from student_fanyong group by name,sex having sex='男';
```
* 多表查询
```sql
/*等值连接：查询两表符合条件的结果*/
select s*name from student s1,student_fanyong s2 where s*stuno=s*stuno ;
/*自连接*/
select s*name from student_fanyong s1,student_fanyong s2 where s*stuno=s*stuno;
/*不等连接：除去等值连接的连接运算*/
select s*name from student s1,student_fanyong s2 where s*stuno<>s*stuno;
/*外部链接：查询两表符合条件的结果和自表其他的结果*/
select s*name from student s1,student_fanyong s2 where s*stuno=s*stuno(+);
/*等值连接*/
select s*name from student s1 inner join student_fanyong s2 on s*stuno=s*stuno ;
/*左连接：查询s1表中所有的学生学号和s2中一样的学生姓名和s1表独有中的学生姓名*/
select s*name from student s1 left join on student_fanyong s2 on s*stuno=s*stuno;
/*右连接：查询s1表中所有的学生学号和s2中一样的学生姓名和s2表独有中的学生姓名*/
select s*name from student s1 right join on student_fanyong s2 on s*stuno=s*stuno;
- 修改字段的长度
/*增加长度*/
ALTER TABLE yls_bill_def_val_item MODIFY( Field VARCHAR2(60));
/*减小字段的长度，数据长度必须不大于0新的字段长度，判断字符串长度的函数：lengthc(str)*/
/**创建一个临时表*/
CREATE TABLE fy_temp2(
pk_bill_def_val_item CHAR(20),
field Varchar2(32)
);
/**复制原来的字段*/
INSERT INTO FY_TEMP2
(PK_BILL_DEF_VAL_ITEM, FIELD)
SELECT PK_BILL_DEF_VAL_ITEM, FIELD
FROM FY_TEMP;
/**清空原表的字段*/
UPDATE yls_bill_def_val_item SET Field=NULL;
/**修改字段的字段*/
ALTER TABLE yls_bill_def_val_item MODIFY( Field VARCHAR2(32));
/*放回字段的值*/
UPDATE YLS_BILL_DEF_VAL_ITEM A
SET A.FIELD =
(SELECT B.FIELD
FROM FY_TEMP B
WHERE A.PK_BILL_DEF_VAL_ITEM = B.PK_BILL_DEF_VAL_ITEM);
原文:大专栏 oracle学习笔记