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

# Database Query tool

> Query a SQL database from natural language.

Use Database Query when you want the assistant to translate natural language into SQL over a configured database connection.

## Prerequisites

* An API token. See [Backoffice Developer Console](/en/developer-manual/get-started/developer-console).
* A database connection string you can share with Zylon.

## Requirements

* Tool spec: `{ "name": "database_query", "type": "database_query_v1" }`
* `tool_context`: one `sql_database` context with `connection_string`

## Basic request and response

This example validates a request that enables database query. For validation, it sets `tool_choice` to `none` so the validator doesn’t try to connect.

```bash theme={null}
curl -X POST "https://{BASE_URL}/api/gpt/v1/messages/validate" \
  -H "Authorization: Bearer {API_TOKEN}" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "default",
    "max_tokens": 128,
    "messages": [
      { "role": "user", "content": "What were total Q1 subscriptions by plan?" }
    ],
    "tools": [
      { "name": "database_query", "type": "database_query_v1" }
    ],
    "tool_choice": { "type": "none" },
    "tool_context": [
      {
        "type": "sql_database",
        "connection_string": "postgresql://{username}:{password}@db.example.com:5432/analytics",
        "schemas": ["public"],
        "ssl": true
      }
    ]
  }'
```

Example response:

```json theme={null}
{ "valid": true, "errors": null }
```

To run the request, send the same body to `POST /messages` and set `tool_choice` to `{ \"type\": \"auto\" }`.

## Tips

* Use a read-only database user.
* Limit schemas to reduce inspection time.

## Next steps

* Learn how messages return tool blocks: [Messages](/en/developer-manual/build-with-zylon/working-with-messages)