CREATE TABLE customer(
id int( 11 ) NOT NULL AUTO_INCREMENT ,
name varchar( 255 ) ,
lastname varchar( 255 ) ,
age int( 11 ),
PRIMARY KEY (id)
) TYPE=INNODB;
CREATE TABLE book(
id int( 11 ) NOT NULL AUTO_INCREMENT ,
title varchar( 255 ) ,
author varchar( 255 ) ,
customer_fk int( 11 ),
available TINYINT NOT NULL,
PRIMARY KEY ( id ),--這里只是定義主索引
INDEX (customer_fk), --定義索引，且它一定是int或integer類型
CONSTRAINT book_customer FOREIGN KEY (customer_fk) REFERENCES customer(id) --外鍵必須是外表主鍵,這里是參照customer的id
)TYPE=INNODB;
以上就已經(jīng)成功定義了外鍵,下面是級(jí)聯(lián)刪除!
--constraint約束
-- ALTER TABLE book ADD CONSTRAINT book_customer FOREIGN KEY ( customer_fk ) REFERENCES customer( id ) ON UPDATE RESTRICT ON DELETE RESTRICT ;--級(jí)聯(lián)刪除
posted on 2009-03-04 18:38
fl1429 閱讀(1351)
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Mysql/Sqlserver/Oracle