Table Relationships

Types of Relationships

One-to-One (1:1)

A one-to-one relationship occurs when a single row in Table A is linked to a single row in Table B. Each record in Table A has a direct and unique relationship with a single record in Table B.

For example, consider a Users table and a Profiles table:

• Each user in the Users table corresponds to a unique profile in the Profiles table.

• The Profiles table will have a foreign key _user_id that references the _id field in the Users table.

One-to-Many (1:Many)

A one-to-many relationship occurs when a single row in Table A is linked to multiple rows in Table B. Each record in Table A can have multiple related records in Table B, but each record in Table B has only one corresponding record in Table A.

For example, consider a Categories table and a Products table:

• Each category in the Categories table can include multiple products from the Products table.

• The Products table will have a foreign key _category_id that references the _id field in the Categories table.

Many-to-Many (Many:Many)

A many-to-many relationship occurs when multiple rows in Table A are linked to multiple rows in Table B. Each record in Table A can have many corresponding records in Table B and vice versa.

For example, consider a Students table and a Courses table:

• Each student can enroll in multiple courses.

• Each course can have multiple students enrolled.

• This relationship is typically implemented using a junction table, such as an Enrollments table, which contains foreign keys _student_id and _course_id that reference the _id field in the Students and Courses tables, respectively.

Populating Data

When working with functions in Twidget, you can use the _id fields to query related data and populate the complete data set into the main object.