BigQuery: Relationships between Tables/Views

Introduction

Let's say we have the following tables in our database: authors, passport_infos, articles and tags.

Table relationships

The tables/views in any relational database are typically related to each other via one of the following types of table relationships:

Type	Example	Meaning
`one-to-one`	`owner` and `passport_infos`	<ul><li> an `owner` can have one `passport_info` </li><li> a `passport_info` can have one `owner` </li></ul>
`one-to-many`	`authors` and `articles`	<ul><li> an `author` can have many `articles` </li><li> an `article` can have one `author` </li></ul>
`many-to-many`	`articles` and `tags`	<ul><li> an `article` can have many `tags` </li><li> a `tag` can have many `articles` </li></ul>

GraphQL schema relationships {#pg-graphql-relationships}

Each table relationship, as you can see from the above section, will have two component relationships (one in either direction) in the GraphQL schema. These relationships can be one of the following types:

Type	Example	Meaning
`object relationship` (one-to-one)	an `article` can have one `author`	an `article` object will have a single nested author object called `author`
`array relationship` (one-to-many)	an `author` can have many `articles`	an `author` object will have an array of nested article objects called `articles`

:::info Note

The relationship name is used to refer to the nested objects in queries. For example, "articles" of an author and "author" of an article.

:::

Managing GraphQL relationships

See the following to manage the object/array relationships between tables/views for the GraphQL schema: