产品
CREATE TABLE if NOT EXISTS `PRODUCTS` (
`ID` INT unsigned NOT NULL AUTO_INCREMENT,
`COMPANY_ID` INT(10) unsigned NOT NULL,
`PRODUCT_CODE` VARCHAR(5) NOT NULL,
`PRODUCT_NAME` VARCHAR(15) NOT NULL,
`UNIT_TYPE` VARCHAR(1) NULL,
UNIQUE INDEX UNIQUE_COMAPNY_PRODUCT_CODE (`COMPANY_ID`, `PRODUCT_CODE`),
CONSTRAINT `PRODUCT_COMPANY_ID_FK` FOREIGN KEY (`COMPANY_ID`) REFERENCES `companies` (`ID`) ON DELETE CASCADE ON UPDATE CASCADE
)我想给上面的“产品代码”做一个外键。。。。。。这是我的密码
ALTER TABLE services
ADD COLUMN `PRODUCT_CODE` VARCHAR(5),
// ADD foreign `PRODUCT_CODE` that refrences to `PRODUCT_CODE` in PRODUCTS table那么如何在mysql中完成上面的注解行呢？？
1条答案
按热度按时间shyt4zoc1#
外键中引用的列可以是主键，也可以是唯一的。首先需要在上添加索引
PRODUCT_CODE. 我把它当作UNIQUE```ALTER TABLE PRODUCTS ADD UNIQUE INDEX (PRODUCT_CODE);
ALTER TABLE services
ADD FOREIGN KEY (PRODUCT_CODE) REFERENCES PRODUCTS(PRODUCT_CODE);
ALTER TABLE services
ADD COLUMN
PRODUCT_CODEVARCHAR(5),ADD FOREIGN KEY (PRODUCT_CODE) REFERENCES PRODUCTS(PRODUCT_CODE);