oracle约束条件

CREATE   TABLE BOOKINFO
(
    BOOKID    NUMBER,
    BOOKNAME   VARCHAR2(20),
    PUBLISH     VARCHAR2(20),
    PUBDATE    VARCHAR2(20),
    PRICE         NUMBER(6,3),
    AUTHOR    VARCHAR2(20),
    STORE      VARCHAR2(1),
    READER   NUMBER,
    REMARKS VARCHAR2(50),
    CONSTRAINT    CK_PRICE    CHECK(PRICE>=10 AND PRICE <= 100)
);

alter table BOOKINFO add CONSTRAINT    CK_PRICE    CHECK(PRICE>=10 AND PRICE <= 100)

CREATE TABLE    BOOKINFO
(
BOOKID    NUMBER    NOT NULL,
BOOKNAME   VARCHAR2(20)     NOT NULL,
PUBLISH    VARCHAR2(20),
PUBDATE   VARCHAR2(20),
PRICE     NUMBER(6,3),
AUTHOR     VARCHAR2(20),
STORE      VARCHAR2(1),
READER    NUMBER,
REMAERKS    VARCHAR2(50)
);

CREATE TABLE    BOOKINFO
(
BOOKID    NUMBER,
BOOKNAME   VARCHAR2(20),
PUBLISH    VARCHAR2(20),
PUBDATE   VARCHAR2(20),
PRICE     NUMBER(6,3),
AUTHOR     VARCHAR2(20),
STORE      VARCHAR2(1),
READER    NUMBER,
REMAERKS    VARCHAR2(50),
CONSTRAINT    CK_BOOKID    CHECK(BOOKID IS NOT NULL),
CONSTRAINT    CK_BOOKNAME   CHECK(BOOKNAME IS NOT NULL)
);

alter table BOOKINFO add CONSTRAINT    CK_PRICE    CHECK(BOOKID IS NOT NULL)

alter table test
drop constraint 约束名;