اسنیپت‌ها، ترفندها و کدهای کاربردی

-- One-to-One (1:1)
CREATE TABLE Users (
    Id INT PRIMARY KEY
);

CREATE TABLE UserProfiles (
    Id INT PRIMARY KEY,
    UserId INT UNIQUE,
    FOREIGN KEY (UserId) REFERENCES Users(Id)
);


-- One-to-Many (1:N)
CREATE TABLE Customers (
    Id INT PRIMARY KEY
);

CREATE TABLE Orders (
    Id INT PRIMARY KEY,
    CustomerId INT,
    FOREIGN KEY (CustomerId) REFERENCES Customers(Id)
);


-- Many-to-Many (N:N)
CREATE TABLE Students (
    Id INT PRIMARY KEY
);

CREATE TABLE Courses (
    Id INT PRIMARY KEY
);

CREATE TABLE StudentCourses (
    StudentId INT,
    CourseId INT,

    PRIMARY KEY (StudentId, CourseId),

    FOREIGN KEY (StudentId) REFERENCES Students(Id),
    FOREIGN KEY (CourseId) REFERENCES Courses(Id)
);