sql - 多个外键？

Question

我有一张表格，用来记录从一个供应商向另一个供应商运送产品的天数和成本。我们（出色地：p）将运输供应商（FedEx、UPS）和产品处理供应商（Think...Dunder Mifflin）存储在“供应商”表中。所以，我的 SHIPPING_DETAILS 表中有三列都引用了 VENDOR.no。出于某种原因，MySQL 不允许我将所有三个定义为外键。有任何想法吗？

CREATE TABLE SHIPPING_GRID(  
    id INT NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT 'Unique ID for each row',  
    shipping_vendor_no INT(6) NOT NULL COMMENT 'Foreign key to VENDOR.no for the shipping vendor (vendors_type must be 3)',  
    start_vendor_no INT(6) NOT NULL COMMENT 'Foreign key to VENDOR.no for the vendor being shipped from',  
    end_vendor_no INT(6) NOT NULL COMMENT 'Foreign key to the VENDOR.no for the vendor being shipped to',  
    shipment_duration INT(1) DEFAULT 1 COMMENT 'Duration in whole days shipment will take',  
    price FLOAT(5,5) NOT NULL COMMENT 'Price in US dollars per shipment lbs (down to 5 decimal places)',  
    is_flat_rate TINYINT(1) DEFAULT 0 COMMENT '1 if is flat rate regardless of weight, 0 if price is by lbs',  
    INDEX (shipping_vendor_no),  
    INDEX (start_vendor_no),  
    INDEX (end_vendor_no),  
    FOREIGN KEY (shipping_vendor_no) REFERENCES VENDOR (no),  
    FOREIGN KEY (start_vendor_no) REFERENCES VENDOR (no),  
    FOREIGN KEY (end_vendor_no) REFERENCES VENDOR (no)  
) TYPE = INNODB;

编辑删除双主键定义...

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是的，不幸的是，这并没有解决它。现在我得到：

无法创建表'./删除我的数据库名称/SHIPPING_GRID.frm'（错误号：150）

做一个 phpinfo() 告诉我这个mysql：

客户端 API 版本 5.0.45

是的，VENDOR.no 是 int(6) 类型。

Answer 1

您定义了两次主键。尝试：

CREATE TABLE SHIPPING_GRID(  
    id INT NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT 'Unique ID for each row',  
    shipping_vendor_no INT(6) NOT NULL COMMENT 'Foreign key to VENDOR.no for the shipping vendor (vendors_type must be 3)',  
    start_vendor_no INT(6) NOT NULL COMMENT 'Foreign key to VENDOR.no for the vendor being shipped from',  
    end_vendor_no INT(6) NOT NULL COMMENT 'Foreign key to the VENDOR.no for the vendor being shipped to',  
    shipment_duration INT(1) DEFAULT 1 COMMENT 'Duration in whole days shipment will take',  
    price FLOAT(5,5) NOT NULL COMMENT 'Price in US dollars per shipment lbs (down to 5 decimal places)',  
    is_flat_rate TINYINT(1) DEFAULT 0 COMMENT '1 if is flat rate regardless of weight, 0 if price is by lbs',  
    INDEX (shipping_vendor_no),  
    INDEX (start_vendor_no),  
    INDEX (end_vendor_no),  
    FOREIGN KEY (shipping_vendor_no) REFERENCES VENDOR (no),  
    FOREIGN KEY (start_vendor_no) REFERENCES VENDOR (no),  
    FOREIGN KEY (end_vendor_no) REFERENCES VENDOR (no)  
) TYPE = INNODB;

VENDOR 主键必须是 INT(6)，并且两个表都必须是 InnoDB 类型。

Answer 2

能否提供 VENDOR 表的定义

我想到了。VENDOR 表是 MyISAM ...（编辑了您的答案，告诉我让它们都成为 INNODB ；））

（有什么理由不将 VENDOR 类型切换到 INNODB 吗？）

Answer 3

我在这里运行代码，错误消息显示（这是正确的！）您将id字段设置为主键两次。