> For the complete documentation index, see [llms.txt](https://docs.whalesync.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.whalesync.com/connectors/google-sheets/foreign-keys.md).

# Foreign keys

An explanation of how to set up foreign key (aka reference) field relationships in Sheets

Foreign keys allow you to create relationships between tables in your synced Google Sheets.

<figure><img src="https://2481481593-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FtLaMDbvbGOow76E8CnqW%2Fuploads%2Fgit-blob-0ec453c61a707f166b0ccd8223ddff4ad5d150e5%2FSheets.png?alt=media" alt=""><figcaption><p>An example of a foreign key field relating People to Tasks</p></figcaption></figure>

### How to set up foreign keys

#### 1. Define a foreign key column

Create a column in the following format: `Related_[Table Name]`

<figure><img src="https://2481481593-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FtLaMDbvbGOow76E8CnqW%2Fuploads%2Fgit-blob-79163d21b73e2a17eb0b8c9d12b1a868a239d642%2FRelated%20People.png?alt=media" alt=""><figcaption><p>Here our column name is "Related_People" because we're relating Tasks to the People table</p></figcaption></figure>

{% hint style="info" %}
Capitalization matters, so make sure the table name matches exactly.
{% endhint %}

#### 2. Map the Foreign Key field in Whalesync

<figure><img src="https://2481481593-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FtLaMDbvbGOow76E8CnqW%2Fuploads%2Fgit-blob-0cb18d47e166034856ca6d9ed18493291f505622%2FMap%20fields.png?alt=media" alt=""><figcaption></figcaption></figure>

Google Sheets foreign key fields map with [reference fields](/features/additional-features/reference-fields.md) in other apps.

{% hint style="info" %}
You will likely need to click "Referesh" to ensure Whalesync sees your newest fields
{% endhint %}

#### 3. Insert Foreign Key values

To link a row from another table to your Foreign Key column:

1. Copy the Whalesync ID of the row you want to reference.
2. Paste the Whalesync ID into the foreign key column.

<figure><img src="https://2481481593-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FtLaMDbvbGOow76E8CnqW%2Fuploads%2Fgit-blob-4b8e3c0278dabab5cd0ce6ecf826d8fae51b492c%2Fvalues.gif?alt=media" alt=""><figcaption><p>Copying the Whalesync ID from a person in the People's table into the "Related_People" column in Tasks</p></figcaption></figure>

* The Whalesync ID is a unique identifier for each row.
* It is Column A in each mapped table in Google Sheets, and it is hidden.
* Click on the arrow to unhide the Whalesync ID column.

{% hint style="warning" %}
**Avoid making any changes to the Whalesync ID column to avoid sync issues.**
{% endhint %}