具有 3 个表和“此列没有匹配的唯一键或主键”的简单数据库

Question

我有三个表，两个是独立创建的，第三个是为了包含前两个的一些输入而创建的。前两个表没有问题，但是，当我尝试创建第三个时，出现错误：

Error report -
ORA-02270: no matching unique or primary key for this column-list
02270. 00000 -  "no matching unique or primary key for this column-list"
*Cause:    A REFERENCES clause in a CREATE/ALTER TABLE statement
           gives a column-list for which there is no matching unique or primary
           key constraint in the referenced table.
*Action:   Find the correct column names using the ALL_CONS_COLUMNS
           catalog view

问题是，我通过从前两个表中复制/粘贴列名/定义来创建第三个表，但我仍然收到这个荒谬的错误消息。现在我想知道列的顺序，尤其是约束的顺序是否重要。

表格：

1. comm_Customers

CREATE TABLE comm_Customers (
    custID NUMBER(6) NOT NULL,
    FirstName VARCHAR2(10) NOT NULL,
    LastName VARCHAR2(15) NOT NULL,
    HomeCountry VARCHAR2(2) NOT NULL,
    HomeState_Prov VARCHAR2(2) NOT NULL,
    HomeCity VARCHAR2(20) NOT NULL,
    HomeAddress VARCHAR2(25) NOT NULL,
    Phone NUMBER(10) NOT NULL,
    Email VARCHAR2(15) NOT NULL,
    ShippCountry VARCHAR2(2) NOT NULL,
    ShippState_Prov VARCHAR2(2) NOT NULL,
    ShippCity VARCHAR2(10) NOT NULL,
    ShippAddress VARCHAR2(15) NOT NULL,  
    CONSTRAINT comm_customers_custid_pk PRIMARY KEY (custID)    
);

1. comm_Items

CREATE TABLE comm_Items (
    itemID NUMBER(4) NOT NULL,
    ItemCat VARCHAR2(3) NOT NULL,
    ItemQty NUMBER(4) NOT NULL,
    SalePrice NUMBER(6,2) NOT NULL,
    CostPrice NUMBER(6,2) NOT NULL,
    ItemDesc VARCHAR2(15),
    CONSTRAINT comm_items_itemid_pk PRIMARY KEY (itemID)
);

1. 给出错误的comm_Orders

CREATE TABLE comm_Orders (
    orderID NUMBER(10) NOT NULL,
    OrderQty NUMBER(4) NOT NULL,
    OrderDate DATE NOT NULL,
    Shipped VARCHAR2(1),
    ShippedDate DATE,    
    custID NUMBER(6) NOT NULL,
    Phone NUMBER(10) NOT NULL,
    Email VARCHAR2(15) NOT NULL,
    ShippCountry VARCHAR2(2) NOT NULL,
    ShippState_Prov VARCHAR2(2) NOT NULL,
    ShippCity VARCHAR2(10) NOT NULL,
    ShippAddress VARCHAR2(15) NOT NULL,    
    itemID NUMBER(4) NOT NULL,    
    SalePrice NUMBER(6,2) NOT NULL,
    
    CONSTRAINT comm_order_orderid_pk PRIMARY KEY (orderID),
    
    CONSTRAINT comm_order_custid_fk FOREIGN KEY (custID) 
    REFERENCES comm_Customers(custID),
    
    CONSTRAINT comm_order_phone_fk FOREIGN KEY (Phone) 
    REFERENCES comm_Customers(Phone),
    
    CONSTRAINT comm_order_email_fk FOREIGN KEY (Email) 
    REFERENCES comm_Customers(Email),
    
    CONSTRAINT comm_order_shippcountry_fk FOREIGN KEY (ShippCountry) 
    REFERENCES comm_Customers(ShippCountry),
    
    CONSTRAINT comm_order_shippstate_prov_fk FOREIGN KEY (ShippState_Prov) 
    REFERENCES comm_Customers(ShippState_Prov),

    CONSTRAINT comm_order_shippcity_fk FOREIGN KEY (ShippCity) 
    REFERENCES comm_Customers(ShippCity),

    CONSTRAINT comm_order_shippaddress_fk FOREIGN KEY (ShippAddress) 
    REFERENCES comm_Customers(ShippAddress),     
    
    CONSTRAINT comm_order_itemid_fk FOREIGN KEY (itemID) 
    REFERENCES comm_Items(itemID), 
    
    CONSTRAINT comm_order_saleprice_fk FOREIGN KEY (SalePrice) 
    REFERENCES comm_Items(SalePrice)     
    
    ON DELETE CASCADE,
    
    CONSTRAINT comm_order_shipped_chk CHECK (Shipped IN ('Y','N'))    
);

Answer 1

对customers 和items 的非主键列的引用确实会引发错误。

归根结底，您不应该复制参考表中的信息。一个外键就足够了。

所以：

CREATE TABLE comm_Orders (
    orderID NUMBER(10) NOT NULL,
    OrderQty NUMBER(4) NOT NULL,
    OrderDate DATE NOT NULL,
    Shipped VARCHAR2(1),
    ShippedDate DATE,    
    custID NUMBER(6) NOT NULL,
    itemID NUMBER(4) NOT NULL,    
    CONSTRAINT comm_order_orderid_pk PRIMARY KEY (orderID),
    CONSTRAINT comm_order_custid_fk  FOREIGN KEY (custID) REFERENCES comm_Customers(custID),    
    CONSTRAINT comm_order_itemid_fk  FOREIGN KEY (itemID) REFERENCES comm_Items(itemID), 
    CONSTRAINT comm_order_shipped_chk CHECK (Shipped IN ('Y','N'))
);

然后，每当您需要从参照表中恢复信息时，您都可以使用外键join 它。假设您想要客户的电话：

select o.*, c.phone
from comm_orders o
inner join comm_customers c on c.custid = o.custid