爲什麼我的SQL表格不是3個正常格式

Question

我已經創建了這個數據庫。看起來它工作正常，除了我被告知我的表「事件」不是第三範式。我不明白爲什麼它不是第三種正常形式。我認爲這可能是因爲城市和郵政編碼應該始終相同，但大城市可以有多個郵政編碼，而且我沒有看到只爲城市和他們的郵政編碼創建另一個表的重點，相關到事件表。

同樣抱歉，如果某些名稱或屬性使用系統保留的某些名稱命名不正確。我不得不把代碼翻譯成英文，因爲我用我的母語寫了它:)。謝謝你的幫助。

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 

編輯： 你認爲它可以這樣工作嗎？我製作了另一張名爲「位置」的表格，其中包含以前在事件表中的所有地址信息，並創建了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

回答這個問題。

你是對的，數據庫不是第三範式。正如你已經確定的那樣，有機會規範化各種郵政編碼，城市和街道。這將導致每個郵政編碼（等）的行，你會有每個FKs。

個人而言，我不這樣做。這顯然取決於應用程序，但在我的系統中，我更感興趣的是獲取用戶的地址，而不是擁有特定郵政編碼的所有用戶。

取決於你打算如何使用你的數據第三法線可能不是最有效的方式來存儲你的數據。

Answer 2

根據您的編輯 - 關閉，但我會轉過身來。我給location一個location_id列（PK），刪除其event_id列，然後讓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]) 
) 

再反向外鍵也是如此。

這樣，如果地址需要更正它只需要在一行中糾正 - 這畢竟是歸一化點 - 使得更正只需要應用一次。