One-to-one relationships in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a one-to-one relationship in databases?

A one-to-one relationship means each record in one table is linked to exactly one record in another table, and vice versa.

beginner

How do you represent a one-to-one relationship in GraphQL schema?

You use fields in types that reference each other, often with unique IDs to link exactly one record from one type to one record in another.

intermediate

Why use one-to-one relationships instead of combining data in one type?

To keep data organized, avoid duplication, and separate concerns, especially when some data is optional or sensitive.

intermediate

In GraphQL, how can you ensure a one-to-one relationship is enforced?

By using unique identifiers and resolvers that fetch exactly one related record, and by database constraints like unique foreign keys.

beginner

Give a simple example of a one-to-one relationship in GraphQL types.

type User { id: ID! profile: Profile } type Profile { id: ID! user: User } Each User has one Profile and each Profile belongs to one User.

What does a one-to-one relationship mean?

A One record links to many records in another table

B Many records link to many records in another table

C Each record in one table links to exactly one record in another table

D No records are linked between tables

A one-to-one relationship means each record in one table is linked to exactly one record in another table.

In GraphQL, how do you link two types in a one-to-one relationship?

A By using arrays to hold multiple records

B By merging both types into one

C By ignoring relationships

D By adding a field in one type that references the other type

You link two types by adding a field in one type that references the other type.

Why might you separate data into two types with a one-to-one relationship?

A To make queries slower

B To organize data and keep sensitive info separate

C To duplicate data unnecessarily

D To avoid using IDs

Separating data helps organize it and keeps sensitive or optional info separate.

Which database constraint helps enforce one-to-one relationships?

A Unique foreign key

B Non-unique index

C Primary key on both tables

D No constraints needed

A unique foreign key ensures each record links to only one record in the related table.

In a GraphQL one-to-one example, what does the User type typically contain?

A A field referencing Profile

B An array of Profiles

C No fields referencing other types

D Multiple unrelated fields

User type contains a field referencing Profile to show the one-to-one link.

Explain what a one-to-one relationship is and how you would model it in GraphQL.

Think about how each record links to exactly one record in another type.

Describe why one-to-one relationships are useful and give a simple GraphQL example.

Consider when you want to keep some data separate but connected.