MySQL 1215：无法添加外键约束

Question

您能否介绍为什么CHARGEITEM，INVOICE和PAYMENT可能会失败？我在这里错过了什么？

我检查了这些：

• 所有的PK和FKS是BIGINT列
• 我让他们空列
• 删除了约束名称（想他们可能会发生冲突）
• 新增的ON DELETE RESTRICT
• 我也检查过他们都是INNODB。

以下是完整的脚本（表6,8和9是失败）：

CREATE TABLE `BUILDING` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `NAME` varchar(255) DEFAULT NULL, 
    `ADDRESS` varchar(255) DEFAULT NULL, 
    PRIMARY KEY (`ID`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 


CREATE TABLE `ROOM` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `BUILDINGID` BIGINT NULL DEFAULT NULL, 
    `FLOORNUM` varchar(255) DEFAULT NULL, 
    `DOORNUM` varchar(255) DEFAULT NULL, 
    `TYPE` varchar(255) DEFAULT NULL, 
    PRIMARY KEY (`ID`), 
    KEY `BUILDINGID` (`BUILDINGID`), 
    FOREIGN KEY (`BUILDINGID`) REFERENCES `BUILDING` (`ID`) ON DELETE RESTRICT 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `BOOKING` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `ENTRYDATE` datetime DEFAULT NULL, 
    `GUESTNAME` varchar(255) DEFAULT NULL, 
    `GUESTCONTACT` varchar(255) DEFAULT NULL, 
    `GUESTADDRESS` varchar(255) DEFAULT NULL, 
    `GUESTIDTYPE` varchar(255) DEFAULT NULL, 
    `GUESTIDNUM` varchar(255) DEFAULT NULL, 
    `GUESTPASSPORTNUM` varchar(255) DEFAULT NULL, 
    `NOTES` varchar(255) DEFAULT NULL, 
    PRIMARY KEY (`ID`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `BOOKINGROOM` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `BOOKINGID` BIGINT NULL DEFAULT NULL, 
    `ROOMID` BIGINT NULL DEFAULT NULL, 
    `STARTDATE` date DEFAULT NULL, 
    `ENDDATE` date DEFAULT NULL, 
    PRIMARY KEY (`ID`), 
    KEY `BOOKINGID` (`BOOKINGID`), 
    KEY `ROOMID` (`ROOMID`), 
    FOREIGN KEY (`BOOKINGID`) REFERENCES `BOOKING` (`ID`) ON DELETE RESTRICT, 
    FOREIGN KEY (`ROOMID`) REFERENCES `ROOM` (`ID`) ON DELETE RESTRICT 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 


CREATE TABLE `CHARGE` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `CHARGEGROUP` varchar(255) DEFAULT NULL, 
    `CHARGECODE` varchar(255) DEFAULT NULL, 
    `NOTES` varchar(255) DEFAULT NULL, 
    `UNIT` varchar(255) DEFAULT NULL, 
    `UNITRATE` double NOT NULL, 
    PRIMARY KEY (`ID`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `CHARGEITEM` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `BOOKINGID` BIGINT NULL DEFAULT NULL, 
    `ROOMID` BIGINT NULL DEFAULT NULL, 
    `CHARGEID` BIGINT NULL DEFAULT NULL, 
    `ENTRYSTAFFID` BIGINT NULL DEFAULT NULL, 
    `ENTRYDATE` datetime DEFAULT NULL, 
    `VALUEDATE` date DEFAULT NULL, 
    `UNIT` varchar(255) DEFAULT NULL, 
    `UNITRATE` double NOT NULL, 
    `UNITS` double NOT NULL, 
    `AMOUNT` double NOT NULL, 
    `NOTES` varchar(255) DEFAULT NULL, 
    `INVOICEID` BIGINT NULL DEFAULT NULL, 
    PRIMARY KEY (`ID`), 
    KEY `INVOICEID` (`INVOICEID`), 
    KEY `ROOMID` (`ROOMID`), 
    KEY `BOOKINGID` (`BOOKINGID`), 
    KEY `CHARGEID` (`CHARGEID`), 
    FOREIGN KEY (`INVOICEID`) REFERENCES `INVOICE` (`ID`) ON DELETE RESTRICT, 
    FOREIGN KEY (`ROOMID`) REFERENCES `ROOM` (`ID`) ON DELETE RESTRICT, 
    FOREIGN KEY (`BOOKINGID`) REFERENCES `BOOKING` (`ID`) ON DELETE RESTRICT, 
    FOREIGN KEY (`CHARGEID`) REFERENCES `CHARGE` (`ID`) ON DELETE RESTRICT 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `DROPDOWNENTRY` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `MODULE` varchar(255) DEFAULT NULL, 
    `POSITION` int(11) NOT NULL, 
    `KEY` varchar(255) DEFAULT NULL, 
    `VALUE` varchar(255) DEFAULT NULL, 
    PRIMARY KEY (`ID`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `INVOICE` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `BOOKINGID` varchar(255) NOT NULL, 
    `ENTRYSTAFFID` BIGINT NULL DEFAULT NULL, 
    `ENTRYDATE` datetime DEFAULT NULL, 
    `AUTHSTAFFID` BIGINT NULL DEFAULT NULL, 
    `AUTHDATE` datetime DEFAULT NULL, 
    `NETAMOUNT` double NOT NULL, 
    `TAX1` double NOT NULL, 
    `TAX2` double NOT NULL, 
    `TAX3` double NOT NULL, 
    `TOTALTAX` double NOT NULL, 
    `TOTALINCLTAX` double NOT NULL, 
    PRIMARY KEY (`ID`), 
    KEY `BOOKINGID` (`BOOKINGID`), 
    FOREIGN KEY (`BOOKINGID`) REFERENCES `BOOKING` (`ID`) ON DELETE RESTRICT 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `PAYMENT` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `INVOICEID` BIGINT NULL DEFAULT NULL, 
    `AMOUNTPAID` double NOT NULL, 
    `PAYMODE` varchar(255) DEFAULT NULL, 
    `ENTRYDATE` datetime DEFAULT NULL, 
    `VALUEDATE` date DEFAULT NULL, 
    `REALISATIONDATE` date DEFAULT NULL, 
    `BANKCODE` varchar(255) DEFAULT NULL, 
    `INSTRUMENTNUM` varchar(255) DEFAULT NULL, 
    `POSCODE` varchar(255) DEFAULT NULL, 
    `REALISATIONSTATUS` varchar(255) DEFAULT NULL, 
    `NOTES` varchar(255) DEFAULT NULL, 
    PRIMARY KEY (`ID`), 
    KEY `INVOICEID` (`INVOICEID`), 
    FOREIGN KEY (`INVOICEID`) REFERENCES `INVOICE` (`ID`) ON DELETE RESTRICT 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `RESERVATION` (
    `ID` BIGINT NOT NULL AUTO_INCREMENT, 
    `ENTRYDATE` datetime DEFAULT NULL, 
    `FROMDATE` date DEFAULT NULL, 
    `TODATE` date DEFAULT NULL, 
    `NUMROOMS` int(11) NOT NULL, 
    `GUESTNAME` varchar(255) DEFAULT NULL, 
    `GUESTCONTACT` varchar(255) DEFAULT NULL, 
    `GUESTADDRESS` varchar(255) DEFAULT NULL, 
    `NOTES` varchar(255) DEFAULT NULL, 
    PRIMARY KEY (`ID`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

Answer 1

两个问题：当你在另一个表指存在

• INVOICES犯规。在引用之前定义表格或在创建所有表格后定义约束。

• 在INVOICES表中，您正在定义数据类型varchar（255），但在外键中，它指向一个bigint列 - 不起作用。

  在INVOICES表，

  `BOOKINGID` varchar(255) NOT NULL, 
  

  将其更改为：

  `BOOKINGID` BIGINT NOT NULL, 
  

固定都在这里 -

http://rextester.com/JAZOUD38011

Answer 2

你的问题就在这里：

ON DELETE RESTRICT：如果在该表中的记录是不指向现有的主键，约束创建将失败。这包括null-值。

当你说你需要可为空值的时候，它不起作用。要么将您的约束设置为ON RESTRICT SET NULL，要么将字段设置为NOT NULL。

Answer 3

数据库不支持转发外键引用。在CHARGEITEM比如你有：

FOREIGN KEY (`INVOICEID`) REFERENCES `INVOICE` (`ID`) ON DELETE RESTRICT, 

然而，INVOICE表CHARGEITEM后创建。因此，这会失败，等等。

两个选项：

• 排队的表，以便它们引用之前创建它们。请注意，这并非总是可行，因为您的数据模型可以有循环引用。
• 首先定义所有表，然后使用alter table add constraint定义所有外键引用。