Oracle表添加主键、外键

时间:2022-09-11 20:17:56

1、创建表的同时创建主键约束

(1)无命名 create table student ( studentid int primary key not null, studentname varchar(8), age int);

(2)有命名 create table students ( studentid int , studentname varchar(8), age int, constraint yy primary key(studentid));

2、删除表中已有的主键约束

(1)无命名可用 SELECT * from user_cons_columns; 查找表中主键名称得student表中的主键名为SYS_C002715 alter table student drop constraint SYS_C002715;

(2)有命名 alter table students drop constraint yy;

3、向表中添加主键约束 alter table student add constraint pk_student primary key(studentid);

4、向表中添加外键约束 ALTER TABLE table_A ADD CONSTRAINT FK_name FOREIGN KEY(id) REFERENCES table_B(id);