SQL 基础

创建模式
create schema <schema_name> authorization <username> 没有指定schema_name时默认是用户名

删除模式
drop schema <schema_name> <cascade | restrict>


创建表
create table student.sc            ;定义表中的两个主码以及外码
(sno char(7),
cno char(4),
grade smallint,
primary key(sno, cno),
foreign key sno references student(sno),
foreign key sno references course(cno)
);                    /*最后一行没有逗号，外码引用的必须是主码*/

修改表
alter table <table_name>
[ add <新列名> <数据类型> [完整性约束] ]
[ drop [完整性约束名] [列名] ]
[ modify <列名> <数据类型> ];

删除表

drop table <表名>;


创建索引
create [unique] [cluster] index <索引名>
on <表名>( <列名> [ <次序> ] [, <列名> [ <次序> ] ] ....);

删除索引
drop index <索引名>


插入元组
insert
into <表名> [ ( <属性列1> [, <属性列2>...] ) ]
values ( <常量1> [, <常量2>] ... )

insert into sc(sno,cno)
values('200215128','1')

修改元组
update <表名>
set <列名> = <表达式> [, <列名> = <表达式> ]...            
[where <条件>];

update student
set sage = 22
where sno = '200215121'

删除元组
delete
from <表名>
[where <条件> ];

delete
from student
where sno = '200215121'


使用视图创建语句建视图，通过视图查询数据:
create view <视图名> [(<列名>[,<列名>]...)]            ;列名要么全部指定，要么全部不指定
as 
<子查询>
[with check option];

drop view <视图名>;


创建用户
create user <username> [with] [DBA | RESOURCE | CONNECT];
create user  zx_root   IDENTIFIED by 'xxxxx@localhost';

删除用户
drop user <username>;


授权
grant <权限> [,<权限> ]...                    ;all privileges, select, update, insert, delete
on <对象类型> <对象名> [,<对象类型> <对象名>]...
to <用户> [,<用户>]...                        ;public
[with grant option];

grant all privileges
on table student, course
to u2, u3;

grant update(sno)
on table student
to u4;

grant insert
on table sc
to u5
with grant option

回收授权
revoke <权限>[,<权限>]...
on <对象类型> <对象名> [,<对象类型> <对象名>]...
from <用户> [,<用户>]...

revoke select
on table sc
from public


创建角色
create role <rolename>

给角色授权
grant <权限> [,<权限>]...
on <对象类型> <对象名>
to <角色> [,<角色>]...

grant <角色1> [,<角色2>]...
to <角色3> [,<角色4>]...
[with admin option]

收回角色权限
revoke <权限> [,<权限>]...
on <对象类型> <对象名>
from <角色> [,<角色>]...

create role r1;

grant select, update, insert
on table student
to r1;

grant r1
to 王平,张明

revoke select
on table student
from r1;


审计

audit alert,update
on sc;

noaudit all
on sc;


实体完整性
primary key(sno,cno);

参照完整性
foreign key sno reference student(sno);

用户定义完整性
create table sc
(sno char(7) not null,
cno char(4) not null,
grade smallint not null,);

create table dept
(deptno number,
dname varchar(9) unique,
);

create table student
(sno char(7) primary key,
ssex char(2) check (ssex in ('男','女')),);

表级用户定义完整性
check (ssex = '女' or sname not like 'ms.%' );            /*男性名字不能以ms.开头*/

完整性约束命名子句
constraint <完整性约束条件名> [primary key短语 | foreign key 短语 | check 短语]

create stable student
(sno number(5)
    constraint c1 check (sno between 90000 and 99999),
sname varchar(20)
    constraint c2 not null,
sage number(3)
    constraint c3 check (sage <30),
ssex varchar(2)
    constraint c4 check (ssex in ('男','女'),
constraint studentKey primary key(sno),
);

alter table student
drop constraint c4;

alter table student
add constraint c4 check (ssex in ('男','女'));

域中完整性限制
create domain genderdomain char(2)
constraint gd check (value in ('男','女'));

alter domain genderdomain
add constraint gd check (value in ('1','0'));

alter domain genderdomain
drop constraint gd;




查询
seletct [ all | distinct ] <目标列表达式> [, <目标列表达式> ]...
from <表名或视图名> [, <表名或视图名> ]...
[ where <条件表达式> ]
[ group by <列名1> [ having <条件表达式> ] ]
[ order by <列名2> [ asc | desc ] ]

表单查询

select sname name,2015-sage year
from student
where sno = 200215121

select sname, sdept, sage
from student
where sage between 20 and 23        /*not between and*/

select sname, ssex
from student
where sdept in ('cs','ma','is')     /*not in*/

select *
from student
where sno like '2002%21'            /*%任意多个字符,_单个字符, [ escape '\' ] 表示'\'为换码字符，not like */

select sno,cno
from sc
where grade is null            /*is not*/

select sno,grade
from sc
where cno = '3'
order by grade desc,sno

select cno, count( distinct sno )
from sc
group by cno

连接查询，嵌套查询

select sname
from student
where sdept = 'cs' and sage < 20            /*or, not*/

select first.cno, second.cpno
from course first, course second
where first.cpno = second.cno                /*<>是不等于*/

select sname
from student
where sno in
    (select sno
    from sc
    where cno = '2' );

select sno,cno
from sc x
where grade >= 
    (select avg(grade)
    from sc y
    where y.sno = x.sno);

select sname,sage
from student
where sage < any
    (select sage
    from student
    where sdept = 'cs');            /*all*/

select sname
from student
where not exists
    (select *
    from course
    where not exists   
        (select *
        from sc
        where sno = student.sno
        and    cno = course.cno ));            /*not exists 没有*/

集合查询:

select * 
from student
where sdept='cs'
union
select *
from student
where sage<=19;

select *
from student
where sdept='cs'
intersect
select *
from student
where sage<=19;

select *
from student
where sdept='cs'
except
select *
from student
where sage<=19;



数据类型
char(n)                长度为n的定长字符串
varchar(n)                最大长度为n的可变字符串
int                    长整形,可写作integer
smallint                短整形
numberic(p,d)            定点数，有p位数字（不包括符号，小数点）组成，小数点后有d位小数
real                    取决于机器精度的浮点数
double precision            取决于机器精度的双精度浮点数
float(n)                浮点数，精度至少为n为数字
date                    日期,YYYY-MM-DD
time                    时间,HH:MM:SS



小问题


"=" 两边可以没有空格



实例：


create DataBase SpjDB
on (name=spj_dat,
filename='D:\Sql_Server\spj_data.mdf',
size=10mb)
log 
on (name=spj_log,
filename='D:\Sql_Server\spj_log.ldf',
size=3mb)


Create table S
(SNO char(4) primary key,
SNAME char(10),
STATUS smallint,
CITY char(12))

insert into s
values('S1','精益','20','天津');

insert into s
values('S2','盛锡','10','北京');


Create table p
(PNO char(4) primary key,
PNAME char(10),
COLOR char(4),
WEIGHT smallint)

insert into P
values('p1','螺母','红','12');
insert into P
values('p2','螺栓','绿','17');
insert into P


Create table J
(JNO char(4) primary key,
PNAME char(10),
CITY char(10))

insert into J
values('J1','三建','北京');
insert into J
values('J2','一汽','长春');
insert into J


Create table SPJ
(SNO char(2),
PNO char(2),
JNO char(2),
QTY smallint)


insert into SPJ
values('S1','P1','J1','200');
insert into SPJ
values('S1','P1','J3','100');