sql建表语句（含：序列、主键）

CREATE TABLESPACE db_news
DATAFILE 'e:\jsp\db\news.dbf'
SIZE 100m;

CREATE USER news IDENTIFIED BY 123456
DEFAULT TABLESPACE db_news;

GRANT CONNECT,RESOURCE TO news;

create table TOPIC
(
tid   INTEGER not null,
tname VARCHAR2(50) not null
)
alter table TOPIC
add constraint TID primary key (TID)

create table NEWS_USERS
(
usid  INTEGER not null,
uname VARCHAR2(20) not null,
upwd  VARCHAR2(60) not null
)
alter table NEWS_USERS
add primary key (USID)

create table NEWS
(
nid         INTEGER not null,
ntid        INTEGER not null,
ntitle      VARCHAR2(200) not null,
nauthor     VARCHAR2(50) not null,
ncreatedate DATE,
npicpath    VARCHAR2(1000),
ncontent    CLOB not null,
nmodifydate DATE,
nsummary    VARCHAR2(500) not null
)

alter table NEWS
add constraint NID primary key (NID)

alter table NEWS
add constraint NEWS_TOPIC foreign key (NTID)
references TOPIC (TID) on delete cascade;

create table COMMENTS
(
cid      INTEGER not null,
cnid     INTEGER not null,
ccontent VARCHAR2(3000) not null,
cdate    DATE,
cip      VARCHAR2(100) not null,
cauthor  VARCHAR2(100) not null
)

alter table COMMENTS
add constraint CID primary key (CID)

alter table COMMENTS
add constraint CIN_NID foreign key (CNID)
references NEWS (NID) on delete cascade

create sequence nid_seq
increment by 1
start with 1
minvalue 1
nomaxvalue
nocycle