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ORACLE中添加删除主键
山炮   ·  2021.0330 09:58:19
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ORACLE中添加删除主键

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)有命名
 alter table students drop constraint yy;
(2)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;
 
3、向表中添加主键约束
 alter table student add constraint pk_student primary key(studentid); 

end;

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Tag:   Oracle基础   主键   
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