# Side effect rules

> A side effect rule creates, updates, or deletes records in other tables when a record is saved, or starts a workflow. Learn when to use each.

A side effect runs after the record is stored, as part of the same database transaction. It can create, update, or delete records in another table, or start a [workflow](/docs/workflows). Use it to keep related tables in step: write a history entry when a status changes, update an order when a line changes, create a task when a job is booked.

## Create a side effect

1. Open any view on the table, click **Settings**, choose **Business Rules**, and click **New rule**.
2. Enter a **Name** and set the **Rule type** to **Side effect**.
3. Choose the operations under **Runs on**, and optionally add conditions under **When**.
4. Under **What to do**, choose **Create a row**, **Update rows**, **Delete rows**, or **Start a workflow**.
5. Fill in the settings for that action, described below.
6. Under **If this fails**, choose what happens if the action fails.
7. Click **Create rule**.

## Write to another table

- **Create a row**: pick the table under **In which table**, then set each field under **Values to set**.
- **Update rows**: pick the table, describe **Which rows to update**, and set the new values.
- **Delete rows**: pick the table and describe **Which rows to delete**.

Values can be fixed, copied from the record that was saved (before or after the change), or taken from the context, such as the signed-in user or the current time.

> **Warning:** Deletes run without asking for confirmation. Keep the filter under **Which rows to delete** as narrow as possible, for example "Order is this order", so the rule can't remove more than you intend.

## If this fails

| Option | What happens |
| --- | --- |
| **Roll back the whole write** | The original save is undone too. Nothing is stored. Use this when the two tables must always agree. |
| **Log it and let the write through** | The original save is kept and the failure is recorded in the **Execution log**. Use this when the extra write is nice to have. |

## Start a workflow

Choose **Start a workflow** when the follow-up needs more than a database write: sending an email, generating a document, calling another system, or waiting for an approval.

- Pick the workflow. Workflows that accept a record from this table are listed first, under **Accepts a row from this table**.
- Under **Inputs**, fill in the workflow's inputs. **Use the triggering row** passes the saved record.
- Under **Which view**, choose the view the workflow reads the record through. The default is the table's base view.

Once saved, the rule appears in the workflow's **Triggers** panel under **External callers**, so whoever edits the workflow can see what starts it.

> **Note:** The workflow starts after the save has been committed, so it can't roll the save back. If the save is rolled back, the workflow never starts. If the follow-up must succeed for the save to count, write it with a create, update, or delete action instead.

## Examples

| Side effect | Runs on | When | What to do |
| --- | --- | --- | --- |
| Status history | Update | Status changed | Create a row in Status history with the old and new status |
| Book a follow-up | Create | Type is Installation | Create a row in Tasks for the assigned technician |
| Clean up lines | Delete | Always | Delete rows in Order lines where Order is this order |
| Send confirmation | Update | Status changed to Confirmed | Start a workflow that emails the customer |

## Things to keep in mind

- A side effect that writes to another table can run that table's own rules too. Keep these chains short, and avoid rules that write back and forth between two tables.
- If you only need to show a total from related records, a [Rollup column](/docs/columns/rollup) is simpler than a side effect that copies the total on every change.
- Side effects run after computations, validations, and guards have all passed, so they only run for saves that are allowed.

  - [Business rules](/docs/business-rules): How the rule types fit together and run.
  - [Workflows](/docs/workflows): Build processes that send email, create documents, and more.

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Source: https://community.sapugo.app/docs/business-rules/side-effect