不能在MySQL

Question

創建表我有這些表，但只有成功地創造

1. Insurance_Policy_Type
2. Historical_Era
3. 地區
4. 參考
5. 組織
6. Geographic_Area

他們其餘的給我錯誤如，

"Cant create table" on Loan_Item, 
"Reference_Id dont exist" on Historical_Era_Reference 
"error 1064 (4200)" on Loan 

---

CREATE TABLE Insurance_Policy_Type (
Insurance_Policy_Type_Id INT (4), 
Insurance_Policy_Type_Name VARCHAR (30), 
PRIMARY KEY (Insurance_Policy_Type_Id)); 


CREATE TABLE Historical_Era (
Historical_Era_Id INT (4), 
Historical_Era_Name VARCHAR (30), 
PRIMARY KEY (Historical_Era_Id)); 


CREATE TABLE Reference (
Reference_Id INT (4), 
Reference_Name VARCHAR (30), 
Author VARCHAR (30), 
PRIMARY KEY (Reference_Id)); 


CREATE TABLE Region (
Region_Id INT (4), 
Region_Name VARCHAR (30), 
PRIMARY KEY (Region_Id)); 

CREATE TABLE Organisation (
Organisation_Id INT (4), 
Organisation_Name VARCHAR (30), 
PRIMARY KEY (Organisation_Id)); 

CREATE TABLE Items (
Item_Id INT (4), 
Item_Name VARCHAR (30), 
Description VARCHAR (30), 
Insurance_Policy_Type_Id INT (4), 
Geo_Area_Id INT (4) 
PRIMARY KEY (Item_Id), 
FOREIGN KEY (Insurance_Policy_Type_Id) REFERENCES Insurance_Policy_Type(Insurance_Policy_Type_Id), 
FOREIGN KEY (Geo_Area_Id) REFERENCES Geographic_Area(Geo_Area_Id)); 

CREATE TABLE GeoArea_HistEra (
Geo_Area_Id INT (4), 
Historical_Era_Id INT (4), 
FOREIGN KEY (Geo_Area_Id) REFERENCES Geographical_Area(Geo_Area_Id)), 
FOREIGN KEY (Historical_Era_Id) REFERENCES Historical_Era(Historical_Era_Id)); 

CREATE TABLE Historical_Era_Reference (
References_Id INT (4), 
Historical_Era_Id INT (4), 
FOREIGN KEY (Reference_Id) REFERENCES Reference (Reference_Id), 
FOREIGN KEY (Historical_Era_Id) REFERENCES Historical_Era (Historical_Era_Id)); 


CREATE TABLE Loan_Item (
Item_Id INT (4), 
Loan_Id INT (4), 
FOREIGN KEY (Item_Id) REFERENCES Items(Item_Id), 
FOREIGN KEY (Loan_Id) REFERENCES Loan(Loan_Id)); 

CREATE TABLE Geographic_Area (
Geo_Area_Id INT (4), 
Geo_Area_Name VARCHAR (30), 
Region_Id INT (4), 
PRIMARY KEY (Geo_Area_Id), 
FOREIGN KEY (Region_Id) REFERENCES Region (Region_Id)); 

CREATE TABLE Loan (
Loan_Id INT (4), 
Item_Id INT (4) 
Organisation_Id INT(4) 
Loan_Start DAY, 
Loan_End DAY 
FOREIGN KEY (Organisation_Id) REFERENCES Organisation (Organisation_Id), 
FOREIGN KEY (Item_Id) REFERENCES Items (Item_Id)); 

Answer 1

先試後創建表，並添加外鍵。

Answer 2

上面的查詢有很多問題。

1. 您正在爲一個表，該表尚不存在一個參考："FOREIGN KEY (Geo_Area_Id) REFERENCES Geographic_Area(Geo_Area_Id));"首先創建表，然後更新外鍵。

2. 有很多語法錯誤 - 缺少逗號和雙括號。我建議學習如何發現它們，而不是一一指出它們，例如我建議使用IDE。我親自在MySQL Workbench中測試語句。

3. 由於多種原因，查詢可能會產生錯誤150。請查看有關主鍵典型錯誤的非常好的摘要，如FK in the first answer here。