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create table employees (empno number(5) primary key,...)
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create table employees
(empno number(5),
deptno number(3) not null,
constraint emp_pk primary key(empno,deptno)
using index tablespace indx
storage (initial 64K
next 64K
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)
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alter table employees add primary key (empno)
alter table employees add constraint emp_pk primary key (empno)
alter table employees add constraint emp_pk primary key (empno,deptno)
not nullÔ¼Êø(Ö»ÄÜÔÚ×ֶμ¶¶¨ÒåNOT NULLÔ¼Êø,ÔÚͬһ¸ö±íÖпÉÒÔ¶¨Òå¶à¸öNOT NULLÔ¼Êø)
alter table employees modify deptno not null/null
uniqueÔ¼Êø
create table employees
( empno number(5),
ename varchar2(15),
phone varchar2(15),
email varchar2(30) unique,
deptno number(3) not null,
constraint emp_ename_phone_uk unique (ename,phone)
)
alter table employees
add constraint emp_uk unique(ename,phone)
using index tablespace indx
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