> ## Documentation Index
> Fetch the complete documentation index at: https://help.teable.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Lookup

> Reference field values from a linked table through an existing link relationship and keep the data in sync.

Lookup fields are built on **Link** fields. A Lookup field references a selected field from a linked table, so the current table can display data from another table without entering it again.

## Use Cases

| Scenario           | Good for                                                             |
| ------------------ | -------------------------------------------------------------------- |
| Order line items   | After linking a product, show its price, SKU, or category            |
| Ticket handling    | After linking a customer, show phone number, customer tier, or owner |
| Book management    | In a books table, show the author's birthday, nationality, or bio    |
| Project management | From linked tasks, show assignee, due date, or status                |

## Create and Configure

<Steps>
  <Step title="Create a link relationship">
    Before using a Lookup field, create a **Link** field between the two tables.
  </Step>

  <Step title="Choose the field type">
    In the table view, click `+` to add a field and choose **Lookup**.
  </Step>

  <Step title="Choose the link field">
    Choose an existing link field in the current table as the lookup path.
  </Step>

  <Step title="Choose the target field">
    Choose the field to read from the source table, such as an author's birth date, a customer's phone number, or a product price.
  </Step>
</Steps>

## Automatic Sync

After setup, Teable fills the lookup result based on the existing link relationship:

* If the linked record changes, such as choosing a different author, the lookup value updates.
* If source data changes, such as editing an author's birthday, the lookup value refreshes.

## Common Uses

* **Book management**: In a `Books` table, use an `Author` link field to look up `Birth date` from an author details table.
* **Order calculation**: In an `Order line items` table, look up the product price and then use a formula to calculate the total.
* **Customer information sync**: In a tickets table, link a customer and look up the customer's phone number, email, or tier.

## Notes

* **Read-only field**: Lookup fields are **read-only**. You cannot edit the looked-up value from the current table. To change the value, edit the original field in the source table.
* **Single value and multiple values**: If the link relationship is one-to-one, the lookup result is a single value. If the relationship is one-to-many, the lookup result becomes a multi-value array and displays values separated by commas.
* **Data dependencies**: Lookup fields depend on the link field and the source field. If the link field or target field in the source table is deleted, the lookup field stops working.