Send SMS alerts based on database queries (Twilio and Postgres)

This workflow automatically queries a Postgres database to find outlier readings for which SMS notifications have not been sent. This is Workflow 2 in the blog tutorial [Database activity monitoring and alerting](https://blog.n8n.io/database-monitoring-and-alerting-with-n8n/).

Prerequisites

- A Postgres database set up and [credentials](https://docs.n8n.io/integrations/credentials/postgres/) - A Twilio account and [credentials](https://docs.n8n.io/integrations/credentials/twilio/)

Nodes

- [Cron node](https://docs.n8n.io/integrations/core-nodes/n8n-nodes-base.cron/) triggers the workflow every minute, so the database is queried at regular intervals. - [Postgres nodes](https://docs.n8n.io/integrations/nodes/n8n-nodes-base.postgres/) extract values from, and update values in the database. - [Twilio node](https://docs.n8n.io/integrations/nodes/n8n-nodes-base.twilio/) sends an alert SMS about the outlier reading to a specified phone number. - [Set node](https://docs.n8n.io/integrations/core-nodes/n8n-nodes-base.set/) sets the notification value to true.