从ERD创建一个SQL表，实现所有约束

Question

这是我要为其编写SQL查询的ERD图

Answer 1

这是针对Oracle的。您可以类似地创建PRODUCT表，而无需使用FOREIGN KEY：

  CREATE TABLE Orders (
        OrderID int NOT NULL,
        OrderDate date,
        ProductID int,
        PRIMARY KEY (OrderID),
        CONSTRAINT FK_PersonOrder FOREIGN KEY (ProductID)
        REFERENCES PRODUCT(ProductID)
    );

Answer 2

Sql Server

产品表

CREATE TABLE product 
  ( 
     productid   INT PRIMARY KEY IDENTITY(1, 1), 
     productname VARCHAR(50), 
     unitprice   NUMERIC(17, 2) 
  ) 

订单表

CREATE TABLE orders 
  ( 
     orderid     INT PRIMARY KEY IDENTITY(1, 1), 
     OrderDate Datetime, 
     productid   INT, 
     FOREIGN KEY (productid) REFERENCES product(productid) 
  ) 

Answer 3

CREATE TABLE product 
  ( 
     ProductId int,
     ProductnName varchar(50) not null, 
     UnitPrice   NUMERIC(10, 2) 
     CONSTRAINT PRIMARY KEY (ProductId)
  ) 


CREATE TABLE orders 
  ( 
     orderid int auto_increment, 
     OrderDate Datetime, 
     ProductId int, 
     CONSTRAINT PRIMARY KEY (orderid)
     CONSTRAINT FOREIGN KEY (ProductId) REFERENCES product(ProductId)

  )