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

# MySQL Route

> Store MQTT data in MySQL with automatic query execution and SSL support

## MySQL Overview

The `MYSQL` route stores MQTT messages in MySQL databases. It supports SSL connections, parameterized queries, and automatic reconnection for reliable data persistence.

> [!NOTE]
>
> MySQL is ideal for web applications and general-purpose data storage. Its wide ecosystem support makes it a reliable choice for most IoT data persistence needs.

## Basic Syntax

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE SensorDB WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT StoreSensorReading
        WITH SOURCE_TOPIC "sensors/+/reading"
        WITH QUERY "INSERT INTO readings (ts, sensor_id, value) VALUES (NOW(), '{sensor_id}', '{value.json}')"
```

***

## Connection Configuration

### SQL\_CONFIG Parameters

**SERVER** `string` *required*

MySQL server hostname or IP address.

**DATABASE** `string` *required*

Target database name.

**USERNAME** `string` *required*

Database username.

**PASSWORD** `string` *required*

Database password.

> **Optional Settings**
>
> **PORT** `integer`
>
> MySQL port. Default: 3306.
>
> **USE\_SSL** `boolean`
>
> Enable SSL connection. Default: false.
>
> **CONNECTION\_TIMEOUT** `integer`
>
> Connection timeout in seconds. Default: 30.

> [!WARNING]
>
> **Never hardcode credentials in production.** Use environment variables and encrypted secrets to keep sensitive values out of your route definitions:
>
> ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
> WITH SERVER GET ENV "DB_HOST"
> WITH USERNAME GET ENV "DB_USER"
> WITH PASSWORD GET SECRET "DB_PASSWORD"
> ```
>
> See [Environment Variables & Secrets](/v2.14/mqtt-broker/secrets-and-env) for setup and usage.

***

## Event Configuration

### EVENT Parameters

**SOURCE\_TOPIC** `string` *required*

MQTT topic pattern that triggers the INSERT. Supports wildcards.

**QUERY** `string` *required*

SQL INSERT statement with placeholders for dynamic values.

> **Optional Settings**
>
> **DESTINATION\_TOPIC** `string`
>
> MQTT topic to publish query result status.

### Query Placeholders

| Placeholder | Description |
| - | - |
| `{value.json}` | Full JSON payload |
| `{value.json.field}` | Specific field from JSON |
| `{timestamp}` | Message timestamp |
| `{source_topic}` | Original MQTT topic |
| `{field}` | Field extracted from topic path |

***

## Writing Data

**Basic Sensor Storage**

Store sensor readings with timestamps:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE TemperatureDB WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT StoreTemperature
        WITH SOURCE_TOPIC "sensors/+/temperature"
        WITH QUERY "INSERT INTO temperature_readings (recorded_at, sensor_id, value) VALUES (NOW(), '{sensor_id}', {value.json.value})"
```

**With SSL**

Secure connection with SSL:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE SecureDB WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.cloud.com"
        WITH PORT '3306'
        WITH DATABASE "production"
        WITH USERNAME "app_user"
        WITH PASSWORD "secure_password"
        WITH USE_SSL "true"
    ADD EVENT StoreEvent
        WITH SOURCE_TOPIC "events/#"
        WITH QUERY "INSERT INTO events (ts, topic, payload) VALUES (NOW(), '{source_topic}', '{value.json}')"
```

**Multiple Events**

Different tables for different data types:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE MultiTableDB WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    
    ADD EVENT StoreSensorData
        WITH SOURCE_TOPIC "sensors/+/data"
        WITH QUERY "INSERT INTO sensor_data (ts, sensor_id, value) VALUES (NOW(), '{sensor_id}', '{value.json}')"
    
    ADD EVENT StoreAlerts
        WITH SOURCE_TOPIC "alerts/+"
        WITH QUERY "INSERT INTO alerts (ts, alert_type, message) VALUES (NOW(), '{alert_type}', '{value.json}')"
```

**UPSERT**

Insert a record or update it if a duplicate key exists. MySQL uses `ON DUPLICATE KEY UPDATE`:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE DeviceRegistry WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT RegisterDevice
        WITH SOURCE_TOPIC "devices/+/registered"
        WITH QUERY "INSERT INTO devices (device_id, name, area, active, updated_at) VALUES ('{value.json.device_id}', '{value.json.name}', '{value.json.area}', 1, NOW()) ON DUPLICATE KEY UPDATE name = VALUES(name), area = VALUES(area), updated_at = NOW()"
```

`ON DUPLICATE KEY UPDATE` fires only when a row with the same unique key already exists — the existing row is updated instead of inserting a duplicate.

**UPDATE**

Modify existing records when a status or value change arrives:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE DeviceRegistry WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT UpdateDeviceStatus
        WITH SOURCE_TOPIC "devices/+/status"
        WITH QUERY "UPDATE devices SET current_status = '{value.json.status}', last_seen = NOW() WHERE device_id = '{value.json.device_id}'"
```

**DELETE**

Remove records on a decommission or cleanup event:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE DeviceRegistry WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT DecommissionDevice
        WITH SOURCE_TOPIC "devices/+/decommissioned"
        WITH QUERY "DELETE FROM devices WHERE device_id = '{value.json.device_id}' AND active = 0"
```

> [!NOTE]
>
> **Alternative: STORE IN with Models** — Instead of writing EVENT queries, you can bind a [model](/v2.14/lot-language/models/overview) directly to this route. Every `PUBLISH MODEL` call automatically inserts a row — no query needed:
>
> ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
> DEFINE MODEL SensorReading
>     ADD STRING "sensor_id"
>     ADD DOUBLE "value"
>     STORE IN "TemperatureDB"
>         WITH TABLE "temperature_readings"
> ```
>
> See [Data Storage Overview](./overview#with-models-store-in) for the full STORE IN workflow.

***

## Reading Data

EVENTs also support SELECT queries to read data back from the database. Publish a message to the event's `SOURCE_TOPIC`, and the query result is published to `DESTINATION_TOPIC`:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE SensorDB WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT GetLatestReading
        WITH SOURCE_TOPIC "db/query/latest"
        WITH DESTINATION_TOPIC "db/result/latest"
        WITH QUERY "SELECT sensor_id, value FROM readings WHERE sensor_id = '{payload}' ORDER BY ts DESC LIMIT 1"
```

To trigger this query, publish the sensor ID to the source topic:

```
Topic:   db/query/latest
Payload: temp001
```

The query result is published to `db/result/latest`, where your actions or external clients can consume it.

### Timed Polling

EVENTs can also run SELECT queries on a fixed schedule using `WITH EVERY`:

```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
DEFINE ROUTE DeviceRegistry WITH TYPE MYSQL
    ADD SQL_CONFIG
        WITH SERVER "mysql.example.com"
        WITH PORT '3306'
        WITH DATABASE "iot_data"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT PollActiveDevices
        WITH EVERY 10 SECONDS
        WITH DESTINATION_TOPIC "dashboard/devices/active"
        WITH QUERY "SELECT device_id, name, current_status, last_seen FROM devices WHERE active = 1 ORDER BY name"
```

***

## Table Schema Examples

```sql wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}}
-- Basic sensor readings
CREATE TABLE sensor_readings (
    id INT AUTO_INCREMENT PRIMARY KEY,
    recorded_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    sensor_id VARCHAR(50),
    value DOUBLE
);

-- Event log
CREATE TABLE events (
    id INT AUTO_INCREMENT PRIMARY KEY,
    ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    topic VARCHAR(255),
    payload JSON
);
```

***

## Troubleshooting

> **Connection Refused**
>
> * Verify SERVER and PORT are correct
> * Check MySQL is running and accepting connections
> * Verify firewall allows connections on port 3306
> * Check `bind-address` in MySQL configuration

> **Authentication Failed**
>
> * Verify USERNAME and PASSWORD are correct
> * Check user has permissions on the DATABASE
> * Verify user can connect from your host

> **Query Syntax Errors**
>
> * Check placeholder names match topic structure
> * Verify table and column names exist
> * Test query manually in MySQL client first

***

## Next Steps

> **[Data Storage Routes Overview](./overview)**
>
> Compare all storage options.

> **[MariaDB Route](./mariadb)**
>
> Configure MariaDB storage (MySQL-compatible).


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