表的规范化

Question

如何规范化这些表：由于我无法在复合键的部分部分上创建外键。 强文本表示数据库中的主键。

Product(ItemCode, ItemName, SellingPrice)

供应商（供应商名称，Phone，地址）

SupplierProducts(SupplierName, ItemCode, SupplyPrice)

Answer 1

撇开你选择 Supplier.SupplierName 作为 PK，这些表看起来像 Product 之间完美的正常（化）m 对 n 关系和 Supplier 表。在 SupplierProducts.SupplierName 和 SupplierProducts.ItemCode 对上添加一个 unique 索引，就可以了

Answer 2

create table Products
(   ItemCode int auto_increment primary key,
    ItemName varchar(100) not null,
    SellingPrice decimal(10,2) not null,
    updateDt datetime not null
    -- throw in some indexes
);

create table Suppliers
(   SupplierId int auto_increment primary key,
    SupplierName varchar(100) not null -- allows you to change a supplier name
    -- throw in some indexes once you add more columns
);

create table SupplierPhone
(   id int auto_increment primary key,
    SupplierId int not null,
    PhoneNum varchar(20) not null,
    PhoneType int not null, -- have a FK somewhere
    -- FK back to Suppliers
    -- throw in some indexes
    key (SupplierId)
);

create table SupplierAddr
(   id int auto_increment primary key,
    SupplierId int not null,
    Addr1 varchar(100) not null,
    Addr2 varchar(100) not null,
    -- etc all that jazz
    AddrType int not null,  -- have a PK somewhere
    -- FK back to Suppliers
    -- throw in some indexes
    key (SupplierId)
);

create table SupplierProducts
(   id int auto_increment primary key,
    SupplierId int not null,
    ItemCode int not null,
    SupplyPrice decimal(10,2) not null,
    updateDt datetime not null,
    -- FK back to Suppliers
    -- FK back to Products
    -- throw in some indexes
    unique key (SupplierId,ItemCode) -- won't allow dupes on this combo
);

表的规范化

Normalisation of Tables

mysql

sql

database

normalization

relational-database