---
layout: page
title: "SQL Sensor"
description: "Instructions how to integrate SQL sensors into Home Assistant."
date: 2018-02-03 00:22
sidebar: true
comments: false
sharing: true
footer: true
logo: sql.png
ha_category: Sensor
ha_release: 0.63
---

The `SQL` sensor platform enables you to use values from an [SQL](https://en.wikipedia.org/wiki/SQL) database supported by the [sqlalchemy](https://www.sqlalchemy.org) library, to populate a sensor state (and attributes).
This can be used to present statistics about Home Assistant sensors if used with the recorder component database. It can also be used with an external data source.

To configure this sensor, you need to define the sensor connection variables and a list of queries to your `configuration.yaml` file. A sensor will be created for each query:

To enable it, add the following lines to your `configuration.yaml`:

{% raw %}
```yaml
# Example configuration.yaml entry to monitor hass database size in MySQL
sensor:
  - platform: sql
    db_url: mysql://user:password@localhost/hass
    queries:
      - name: HASS DB size
        query: 'SELECT table_schema "database", Round(Sum(data_length + index_length) / 1024, 1) "value" FROM information_schema.tables WHERE table_schema="hass" GROUP BY table_schema;'
        column: 'value'
        unit_of_measurement: kB
```
{% endraw %}

{% configuration %}
db_url:
  description: The URL which points to your database. See [supported engines](/components/recorder/#custom-database-engines).
  required: false
  default: Defaults to the recorder db_url.
  type: string
queries:
  description: List of your queries.
  required: true
  type: map
  keys:
    name:
      description: The name of the sensor.
      required: true
      type: string
    query:
      description: An SQL QUERY string, should return 1 result at most.
      required: true
      type: string
    column:
      description: The field name to select.
      required: true
      type: string
    unit_of_measurement:
      description: Defines the units of measurement of the sensor, if any.
      required: false
      type: string
    value_template:
      description: Defines a template to extract a value from the payload.
      required: false
      type: template
{% endconfiguration %}

## {% linkable_title Examples %}

In this section you find some real life examples of how to use this sensor.

### {% linkable_title Current state of an entity %}

This example shows the previously *recorded* state of sensor *abc123*.

```sql
SELECT * FROM states WHERE entity_id = 'sensor.abc123' ORDER BY id DESC LIMIT 2
```

Note that the SQL sensor state corresponds to the last row of the SQL resultset.

### {% linkable_title Previous state of an entity %}

This example only works with *binary_sensors*:

```sql
SELECT * FROM states WHERE entity_id='binary_sensor.xyz789' GROUP BY state ORDER BY last_changed DESC LIMIT 1
```

### {% linkable_title Database size in Postgres %}

```yaml
- platform: sql
    db_url: postgresql://user:password@host/dbname
    queries:
    - name: db_size
      query: "SELECT (pg_database_size('dsmrreader')/1024/1024) as db_size;"
      column: "db_size"
      unit_of_measurement: MB 
```
