为什么我的SQL表格不是3个正常格式

Question

我已经创建了这个数据库。看起来它工作正常，除了我被告知我的表“事件”不是第三范式。我不明白为什么它不是第三种正常形式。我认为这可能是因为城市和邮政编码应该始终相同，但大城市可以有多个邮政编码，而且我没有看到只为城市和他们的邮政编码创建另一个表的重点，相关到事件表。

同样抱歉，如果某些名称或属性使用系统保留的某些名称命名不正确。我不得不把代码翻译成英文，因为我用我的母语写了它:)。谢谢你的帮助。

Create table [article] 
(
    [id_article] Integer Identity(1,1) NOT NULL, 
    [id_author] Integer NOT NULL, 
    [id_category] Integer NOT NULL, 
    [title] Nvarchar(50) NOT NULL, 
    [content] Text NOT NULL, 
    [date] Datetime NOT NULL, 
Primary Key ([id_article]) 
) 
go 

Create table [author] 
(
    [id_author] Integer Identity(1,1) NOT NULL, 
    [name] Nvarchar(25) NOT NULL, 
    [lastname] Nvarchar(25) NOT NULL, 
    [email] Nvarchar(50) NOT NULL, UNIQUE ([email]), 
    [phone] Integer NOT NULL, UNIQUE ([phone]), 
    [nick] Nvarchar(20) NOT NULL, UNIQUE ([nick]), 
    [passwd] Nvarchar(50) NOT NULL, 
    [acc_number] Integer NOT NULL, UNIQUE ([acc_number]), 
Primary Key ([id_author]) 
) 
go 

Create table [event] 
(
    [id_event] Integer Identity(1,1) NOT NULL, 
    [id_author] Integer NOT NULL, 
    [name] Nvarchar(50) NOT NULL, 
    [date] Datetime NOT NULL, UNIQUE ([date]), 
    [city] Nvarchar(50) NOT NULL, 
    [street] Nvarchar(50) NOT NULL, 
    [zip] Integer NOT NULL, 
    [house_number] Integer NOT NULL, 
    [number_registered] Integer Default 0 NOT NULL Constraint [number_registered] Check (number_registered <= 20), 
Primary Key ([id_event]) 
) 
go 

Create table [user] 
(
    [id_user] Integer Identity(1,1) NOT NULL, 
    [name] Nvarchar(15) NOT NULL, 
    [lastname] Nvarchar(25) NOT NULL, 
    [email] Nvarchar(50) NOT NULL, UNIQUE ([email]), 
    [phone] Integer NOT NULL, UNIQUE ([phone]), 
    [passwd] Nvarchar(50) NOT NULL, 
    [nick] Nvarchar(20) NOT NULL, UNIQUE ([nick]), 
Primary Key ([id_user]) 
) 
go 

Create table [commentary] 
(
    [id_commentary] Integer Identity(1,1) NOT NULL, 
    [content] Text NOT NULL, 
    [id_article] Integer NOT NULL, 
    [id_author] Integer NULL, 
    [id_user] Integer NULL, 
Primary Key ([id_commentary]) 
) 
go 

Create table [category] 
(
    [id_category] Integer Identity(1,1) NOT NULL, 
    [name] Nvarchar(30) NOT NULL, 
Primary Key ([id_category]) 
) 
go 

Create table [registration] 
(
    [id_user] Integer NOT NULL, 
    [id_event] Integer NOT NULL, 
Primary Key ([id_user],[id_event]) 
) 
go 


Alter table [commentary] add foreign key([id_article]) references [article] ([id_article]) on update no action on delete no action 
go 
Alter table [article] add foreign key([id_author]) references [author] ([id_author]) on update no action on delete no action 
go 
Alter table [event] add foreign key([id_author]) references [author] ([id_author]) on update no action on delete no action 
go 
Alter table [commentary] add foreign key([id_author]) references [author] ([id_author]) on update no action on delete no action 
go 
Alter table [registration] add foreign key([id_event]) references [event] ([id_event]) on update no action on delete no action 
go 
Alter table [commentary] add foreign key([id_user]) references [user] ([id_user]) on update no action on delete no action 
go 
Alter table [registration] add foreign key([id_user]) references [user] ([id_user]) on update no action on delete no action 
go 
Alter table [article] add foreign key([id_category]) references [category] ([id_category]) on update no action on delete no action 
go 

编辑： 你认为它可以这样工作吗？我制作了另一张名为“位置”的表格，其中包含以前在事件表中的所有地址信息，并创建了id_event PFK。

Create table [event] 
(
    [id_event] Integer Identity(1,1) NOT NULL, 
    [id_author] Integer NOT NULL, 
    [name] Nvarchar(50) NOT NULL, 
    [datr] Datetime NOT NULL, 
    [number_registered] Integer Default 0 NOT NULL Constraint [number_registered] Check (number_registered <= 20), 
Primary Key ([id_event]) 
) 
go 


Create table [location] 
(
    [city] Char(1) NOT NULL, 
    [id_event] Integer NOT NULL, 
    [street] Char(1) NOT NULL, 
    [house_number] Char(1) NOT NULL, 
    [zip] Char(1) NOT NULL, 
Primary Key ([id_event]) 
) 
go 


Alter table [event] add foreign key([id_auhtor]) references [author] ([id_author]) on update no action on delete no action 
go 

Alter table [location] add foreign key([id_event]) references [event] ([id_event]) on update no action on delete no action 
go 

Answer 1

回答这个问题。

你是对的，数据库不是第三范式。正如你已经确定的那样，有机会规范化各种邮政编码，城市和街道。这将导致每个邮政编码（等）的行，你会有每个FKs。

个人而言，我不这样做。这显然取决于应用程序，但在我的系统中，我更感兴趣的是获取用户的地址，而不是拥有特定邮政编码的所有用户。

取决于你打算如何使用你的数据第三法线可能不是最有效的方式来存储你的数据。

Answer 2

根据您的编辑 - 关闭，但我会转过身来。我给location一个location_id列（PK），删除其event_id列，然后让event是：

Create table [event] 
(
    [id_event] Integer Identity(1,1) NOT NULL, 
    [id_author] Integer NOT NULL, 
    id_location Integer NOT NULL, /* Or null? does every event have to have a location */ 
    [name] Nvarchar(50) NOT NULL, 
    [datr] Datetime NOT NULL, 
    [number_registered] Integer Default 0 NOT NULL Constraint [number_registered] Check (number_registered <= 20), 
Primary Key ([id_event]) 
) 

再反向外键也是如此。

这样，如果地址需要更正它只需要在一行中纠正 - 这毕竟是归一化点 - 使得更正只需要应用一次。