SQL Documentation

Many-to-Many Relationships

A many-to-many relationship occurs when multiple records in one table are associated with multiple records in another table. This is typically modeled using a junction (bridge) table that contains foreign keys referencing each related table.

Conceptual Diagram

Students Courses Enrollments

SQL Example

CREATE TABLE Students (
    StudentID INT PRIMARY KEY,
    Name VARCHAR(100) NOT NULL
);

CREATE TABLE Courses (
    CourseID INT PRIMARY KEY,
    Title VARCHAR(100) NOT NULL
);

CREATE TABLE Enrollments (
    StudentID INT,
    CourseID INT,
    EnrolledOn DATE,
    PRIMARY KEY (StudentID, CourseID),
    FOREIGN KEY (StudentID) REFERENCES Students(StudentID),
    FOREIGN KEY (CourseID) REFERENCES Courses(CourseID)
);

Interactive Query Builder