主键和外键

Question

我有3张桌子

   Student    Loan    Book
 - StudentID  LoanID  BookID

我需要设置哪些外键,因此在给出学生姓名时,搜索该学生的所有贷款并显示书籍详细信息

Answer 1

这是一个模糊的要求的开始:

CREATE TABLE dbo.Students
(
  StudentID INT PRIMARY KEY
  -- , other columns about students
);

CREATE TABLE dbo.Loans
(
  LoanID    INT PRIMARY KEY,
  StudentID INT NOT NULL FOREIGN KEY REFERENCES dbo.Students(StudentID)
  -- , other columns about loans
);

CREATE TABLE dbo.Books
(
  BookID INT PRIMARY KEY,
  -- , other columns about books
);

CREATE TABLE dbo.StudentBooks
(
  StudentID INT NOT NULL FOREIGN KEY REFERENCES dbo.Students(StudentID),
  BookID    INT NOT NULL FOREIGN KEY REFERENCES dbo.Books(BookID)
);