ERROR 1005（HY000）|无法创建表

Question

create table finishedMaterials(
FinishedMaterialID VARCHAR(4) NOT NULL,
FinishedMaterialType VARCHAR(10) NOT NULL,
FinishedMaterialWeight INT(5) NOT NULL,
FinishedMaterialUnits INT(5) NOT NULL,
CONSTRAINT PRIMARY KEY (FinishedMaterialID))ENGINE=INNODB;

create table vehicles(
VehicleID VARCHAR(4) NOT NULL,
VehicleNumber VARCHAR(8),
VehicleType VARCHAR(10) NOT NULL,
VehicleCondition VARCHAR(10) NOT NULL,
VehicleRemarks VARCHAR(100),
CONSTRAINT PRIMARY KEY (VehicleID))ENGINE=INNODB;

create table transport(
TransportID VARCHAR(4) NOT NULL,
VehicleID VARCHAR(4) NOT NULL,
FinishedMaterialID VARCHAR(4) NOT NULL,
FinishedMaterialUnits INT(5) NOT NULL,
FinishedMaterialWeight INT(5) NOT NULL,
CONSTRAINT PRIMARY KEY (TransportID),
CONSTRAINT FOREIGN KEY (VehicleID) REFERENCES vehicles(VehicleID),
CONSTRAINT FOREIGN KEY (FinishedMaterialID) REFERENCES finishedMaterials(FinishedMaterialID),
CONSTRAINT FOREIGN KEY (FinishedMaterialUnits) REFERENCES finishedMaterials(FinishedMaterialUnits),
CONSTRAINT FOREIGN KEY (FinishedMaterialWeight) REFERENCES finishedMaterials(FinishedMaterialWeight))ENGINE=INNODB;

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•此代码有什么问题？是什么导致了这个错误？请帮忙。除了最后一个表之外，所有其他表（包括此代码的前2个）都可以正常工作。

Answer 1

您的最后2个外键未引用主表中的索引键

编辑：他们不应该。 FinishedMaterialWeight和FinsihedMaterialUnits不是finishedMaterials表的唯一键。只需要FinishedMaterialID。

Answer 2

来自维基百科..

＆＃34;外键是关系表中与另一个表的候选键匹配的字段。外键可用于交叉引用表。＆＃ 34;

然而，

CONSTRAINT FOREIGN KEY (FinishedMaterialUnits) REFERENCES finishedMaterials(FinishedMaterialUnits),
CONSTRAINT FOREIGN KEY (FinishedMaterialWeight) REFERENCES finishedMaterials(FinishedMaterialWeight))ENGINE=INNODB;

以上列中，FinishedMaterialUnits和FinishedMaterialWeight不是其表中的候选键。

我认为您的设计有点缺陷，因为这两列不支持表格中的每一行都是唯一的。例如，单位计数可以重复。