> ## 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.

# SQL Server Route

> Store MQTT data in Microsoft SQL Server with automatic query execution and enterprise features

## SQL Server Overview

The `SQLSERVER` route stores MQTT messages in Microsoft SQL Server databases. It supports Windows and SQL authentication, SSL connections, and enterprise features.

<Note>
  SQL Server is ideal for enterprise environments, especially those integrated with Microsoft ecosystems. It offers advanced features like Always On availability and native JSON support.
</Note>

## Basic Syntax

```lot theme={null}
DEFINE ROUTE SensorDB WITH TYPE SQLSERVER
    ADD SQL_CONFIG
        WITH SERVER "sqlserver.example.com"
        WITH PORT '1433'
        WITH DATABASE "IoTData"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT StoreSensorReading
        WITH SOURCE_TOPIC "sensors/+/reading"
        WITH QUERY "INSERT INTO Readings (RecordedAt, SensorId, Value) VALUES (GETDATE(), '{sensor_id}', '{value.json}')"
```

***

## Connection Configuration

### SQL\_CONFIG Parameters

<ParamField path="SERVER" type="string" required>
  SQL Server hostname or IP address. Can include instance name (e.g., `server\instance`).
</ParamField>

<ParamField path="DATABASE" type="string" required>
  Target database name.
</ParamField>

<ParamField path="USERNAME" type="string" required>
  SQL Server username.
</ParamField>

<ParamField path="PASSWORD" type="string" required>
  SQL Server password.
</ParamField>

<AccordionGroup>
  <Accordion title="Optional Settings">
    <ParamField path="PORT" type="integer">
      SQL Server port. Default: 1433.
    </ParamField>

    <ParamField path="USE_SSL" type="boolean">
      Enable SSL connection. Default: false.
    </ParamField>

    <ParamField path="TRUST_SERVER_CERTIFICATE" type="boolean">
      Trust server certificate without validation. Default: false.
    </ParamField>
  </Accordion>
</AccordionGroup>

<Warning>
  **Never hardcode credentials in production.** Use environment variables and encrypted secrets to keep sensitive values out of your route definitions:

  ```lot theme={null}
  WITH SERVER GET ENV "DB_HOST"
  WITH USERNAME GET ENV "DB_USER"
  WITH PASSWORD GET SECRET "DB_PASSWORD"
  ```

  See [Environment Variables & Secrets](/mqtt-broker/secrets-and-env) for setup and usage.
</Warning>

***

## Writing Data

<Tabs>
  <Tab title="Basic Storage">
    Store sensor data in SQL Server:

    ```lot theme={null}
    DEFINE ROUTE SensorStorage WITH TYPE SQLSERVER
        ADD SQL_CONFIG
            WITH SERVER "sqlserver.example.com"
            WITH PORT '1433'
            WITH DATABASE "IoTData"
            WITH USERNAME "iot_user"
            WITH PASSWORD "secure_password"
        ADD EVENT StoreReading
            WITH SOURCE_TOPIC "sensors/+/reading"
            WITH QUERY "INSERT INTO SensorReadings (Timestamp, SensorId, Value) VALUES (GETDATE(), '{sensor_id}', '{value.json}')"
    ```
  </Tab>

  <Tab title="With SSL">
    Secure connection with trusted certificate:

    ```lot theme={null}
    DEFINE ROUTE SecureStorage WITH TYPE SQLSERVER
        ADD SQL_CONFIG
            WITH SERVER "sqlserver.cloud.com"
            WITH PORT '1433'
            WITH DATABASE "Production"
            WITH USERNAME "app_user"
            WITH PASSWORD "secure_password"
            WITH USE_SSL "true"
            WITH TRUST_SERVER_CERTIFICATE "true"
        ADD EVENT StoreEvent
            WITH SOURCE_TOPIC "events/#"
            WITH QUERY "INSERT INTO Events (Timestamp, Topic, Payload) VALUES (GETDATE(), '{source_topic}', '{value.json}')"
    ```
  </Tab>

  <Tab title="Named Instance">
    Connect to a named SQL Server instance:

    ```lot theme={null}
    DEFINE ROUTE InstanceStorage WITH TYPE SQLSERVER
        ADD SQL_CONFIG
            WITH SERVER "server.example.com\\MSSQLSERVER"
            WITH DATABASE "IoTData"
            WITH USERNAME "iot_user"
            WITH PASSWORD "secure_password"
        ADD EVENT StoreData
            WITH SOURCE_TOPIC "data/#"
            WITH QUERY "INSERT INTO DataLog (Timestamp, Topic, Data) VALUES (GETDATE(), '{source_topic}', '{value.json}')"
    ```
  </Tab>

  <Tab title="UPSERT">
    SQL Server uses the `MERGE` statement for upsert logic — insert a row if it doesn't exist, update it if it does:

    ```lot theme={null}
    DEFINE ROUTE DeviceRegistry WITH TYPE SQLSERVER
        ADD SQL_CONFIG
            WITH SERVER "sqlserver.example.com"
            WITH PORT '1433'
            WITH DATABASE "IoTData"
            WITH USERNAME "iot_user"
            WITH PASSWORD "secure_password"
        ADD EVENT RegisterDevice
            WITH SOURCE_TOPIC "devices/+/registered"
            WITH QUERY "MERGE Devices AS target USING (SELECT '{value.json.device_id}' AS device_id, '{value.json.name}' AS name, '{value.json.area}' AS area) AS source ON (target.DeviceId = source.device_id) WHEN MATCHED THEN UPDATE SET Name = source.name, Area = source.area, UpdatedAt = GETDATE() WHEN NOT MATCHED THEN INSERT (DeviceId, Name, Area, Active, UpdatedAt) VALUES (source.device_id, source.name, source.area, 1, GETDATE());"
    ```
  </Tab>

  <Tab title="UPDATE">
    Modify existing records when a status change arrives:

    ```lot theme={null}
    DEFINE ROUTE DeviceRegistry WITH TYPE SQLSERVER
        ADD SQL_CONFIG
            WITH SERVER "sqlserver.example.com"
            WITH PORT '1433'
            WITH DATABASE "IoTData"
            WITH USERNAME "iot_user"
            WITH PASSWORD "secure_password"
        ADD EVENT UpdateDeviceStatus
            WITH SOURCE_TOPIC "devices/+/status"
            WITH QUERY "UPDATE Devices SET CurrentStatus = '{value.json.status}', LastSeen = GETDATE() WHERE DeviceId = '{value.json.device_id}'"
    ```
  </Tab>

  <Tab title="DELETE">
    Remove records on a decommission or cleanup event:

    ```lot theme={null}
    DEFINE ROUTE DeviceRegistry WITH TYPE SQLSERVER
        ADD SQL_CONFIG
            WITH SERVER "sqlserver.example.com"
            WITH PORT '1433'
            WITH DATABASE "IoTData"
            WITH USERNAME "iot_user"
            WITH PASSWORD "secure_password"
        ADD EVENT DecommissionDevice
            WITH SOURCE_TOPIC "devices/+/decommissioned"
            WITH QUERY "DELETE FROM Devices WHERE DeviceId = '{value.json.device_id}' AND Active = 0"
    ```
  </Tab>
</Tabs>

<Info>
  **Alternative: STORE IN with Models** — Instead of writing EVENT queries, you can bind a [model](/lot-language/models/overview) directly to this route. Every `PUBLISH MODEL` call automatically inserts a row — no query needed:

  ```lot theme={null}
  DEFINE MODEL SensorReading
      ADD STRING "sensor_id"
      ADD DOUBLE "value"
      STORE IN "SensorStorage"
          WITH TABLE "SensorReadings"
  ```

  See [Data Storage Overview](./overview#with-models-store-in) for the full STORE IN workflow.
</Info>

***

## 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 theme={null}
DEFINE ROUTE SensorDB WITH TYPE SQLSERVER
    ADD SQL_CONFIG
        WITH SERVER "sqlserver.example.com"
        WITH PORT '1433'
        WITH DATABASE "IoTData"
        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 TOP 1 SensorId, Value FROM Readings WHERE SensorId = '{payload}' ORDER BY RecordedAt DESC"
```

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 theme={null}
DEFINE ROUTE DeviceRegistry WITH TYPE SQLSERVER
    ADD SQL_CONFIG
        WITH SERVER "sqlserver.example.com"
        WITH PORT '1433'
        WITH DATABASE "IoTData"
        WITH USERNAME "iot_user"
        WITH PASSWORD "secure_password"
    ADD EVENT PollActiveDevices
        WITH EVERY 10 SECONDS
        WITH DESTINATION_TOPIC "dashboard/devices/active"
        WITH QUERY "SELECT DeviceId, Name, CurrentStatus, LastSeen FROM Devices WHERE Active = 1 ORDER BY Name"
```

***

## Table Schema Examples

```sql theme={null}
-- Basic sensor readings
CREATE TABLE SensorReadings (
    Id INT IDENTITY(1,1) PRIMARY KEY,
    Timestamp DATETIME2 DEFAULT GETDATE(),
    SensorId NVARCHAR(50),
    Value FLOAT
);

-- JSON storage (SQL Server 2016+)
CREATE TABLE Events (
    Id INT IDENTITY(1,1) PRIMARY KEY,
    Timestamp DATETIME2 DEFAULT GETDATE(),
    Topic NVARCHAR(255),
    Payload NVARCHAR(MAX)
);
```

***

## Troubleshooting

<AccordionGroup>
  <Accordion title="Connection Refused">
    * Verify SERVER and PORT are correct
    * Check SQL Server is running and accepting TCP connections
    * Enable TCP/IP in SQL Server Configuration Manager
    * Verify firewall allows connections on port 1433
  </Accordion>

  <Accordion title="Authentication Failed">
    * Verify USERNAME and PASSWORD are correct
    * Ensure SQL Server authentication is enabled (mixed mode)
    * Check user has permissions on the DATABASE
  </Accordion>

  <Accordion title="SSL/Certificate Errors">
    * Set TRUST\_SERVER\_CERTIFICATE "true" for self-signed certs
    * Verify SSL is configured on SQL Server
  </Accordion>
</AccordionGroup>

***

## Next Steps

<CardGroup cols={2}>
  <Card title="Data Storage Routes Overview" icon="database" href="./overview">
    Compare all storage options.
  </Card>

  <Card title="MongoDB Route" icon="leaf" href="./mongodb">
    Configure MongoDB document storage.
  </Card>
</CardGroup>