oracle--约束（主键、非空、检查）

, sname varchar2(100), sage number(3), ssex char(4), sbirth date, sqq varchar2(30) );

create table student(
       sno number(10),
       sname varchar2(100),
       sage number(3),
       ssex char(4),
       sbirth date,
       sqq varchar2(30),
       constraint pk_student_sno primary key(sno) ---添加主键约束
);

create table student(
       sno number(10),
       sname varchar2(100),
       sage number(3),
       ssex char(4),
       sbirth date,
       sqq varchar2(30)
);
alter table student add constraint pk_student_sno primary key(sno);
alter table student drop constraint pk_student_sno;

 

select * from student for update;
drop table student;

 

非空约束

三种方式

create table student(
       sno number(10) primary key,
       sname varchar2(100) not null,
       sage number(3),
       ssex char(4),
       sbirth date,
       sqq varchar2(30)
);

 

create table student(
       sno number(10) primary key,
       sname varchar2(100)，
       sage number(3),
       ssex char(4),
       sbirth date,
       sqq varchar2(30),
       constraints ck_student_sname check(sname is not null)
);

　

create table student(
       sno number(10) primary key,
       sname varchar2(100),
       sage number(3),
       ssex char(4),
       sbirth date,
       sqq varchar2(30)
       
);

　　alter table student add constraint ch_student_sname check(sname is not null);　　

 

alter table student drop constraint ch_student_sname 

　

检查约束

create table student(
       sno number(10) primary key,
       sname varchar2(100) not null,
       sage number(3) check(sage<150 and sage>0),
       ssex char(4) check(ssex =‘男‘ or ssex = ‘女‘),
       sbirth date,
       sqq varchar2(30)      
);

 

create table student(
       sno number(10) primary key,
       sname varchar2(100) not null,
       sage number(3),
       ssex char(4) check(ssex =‘男‘ or ssex = ‘女‘),
       sbirth date,
       sqq varchar2(30),
       constraint ch_student_sage check(sage<150 and sage>0)      
);

　　

create table student(
       sno number(10) primary key,
       sname varchar2(100) not null,
       sage number(3),
       ssex char(4) check(ssex =‘男‘ or ssex = ‘女‘),
       sbirth date,
       sqq varchar2(30)     
);

alter table student add constraint ch_student_sage check(sage<150 and sage>0);

 

alter table student drop constraint ch_student_sage;

　　

 

 

oracle--约束（主键、非空、检查）

标签：默认值   traints   sel   def   ble   play   lte   one   关键字