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?Oracle??????????????????????????????ID?????????????????????????????

???????????seq_nc_user?????????ID?????1?????????1?

create sequence seq_nc_userincrement by 1start with 1nomaxvalue nocycle cache 10;

???????????nc_user???????ID???????????????????????ID???????????

create table nc_user (    ncid number(9),    name varchar2(50) not null,    mail varchar2(50),    pass varchar2(50),    descb varchar2(255) default 'nice',    age number(9));

??????ID???????????????????????????????????????????0?110???

alter table nc_useradd constraint pk_nc_user primary key(ncid);alter table nc_useradd constraint uk_nc_user unique(name);alter table nc_useradd constraint ck_nc_user check(age > 0 and age < 110);

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alter table nc_userdrop constraint pk_nc_user cascade;alter table nc_userdrop constraint uk_nc_user cascade;alter table nc_userdrop constraint ck_nc_user cascade;

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drop table nc_user;create trigger tri_nc_userbefore insert on nc_user for each rowbegin    select seq_nc_user.nextval into :new.ncid from dual;end;/drop trigger tri_nc_user;

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