---
title: Querying from a Worker
description: Access Analytics Engine data from within a Worker.
image: https://developers.cloudflare.com/core-services-preview.png
---

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# Querying from a Worker

If you want to access Analytics Engine data from within a Worker you can use `fetch` to access the SQL API. The API can return JSON data that is easy to interact with in JavaScript.

## Authentication

In order that your Worker can authenticate with the API you will need your account ID and an API token.

* Your 32 character account ID can be obtained from the Cloudflare dashboard.
* An API token can also be generated in the dashboard. Refer to the [SQL API docs](https://developers.cloudflare.com/analytics/analytics-engine/sql-api/#authentication) for more information on this.

We recommend storing the account ID as an environment variable and the API token as a secret in your worker. This can be done through the dashboard or through Wrangler. Refer to the [Workers documentation](https://developers.cloudflare.com/workers/configuration/environment-variables/) for more details on this.

## Querying

Use the JavaScript `fetch` API as follows to execute a query:

JavaScript

```
const query = "SELECT * FROM my_dataset";const API = `https://api.cloudflare.com/client/v4/accounts/${env.ACCOUNT_ID}/analytics_engine/sql`;const response = await fetch(API, {  method: "POST",  headers: {    Authorization: `Bearer ${env.API_TOKEN}`,  },  body: query,});const responseJSON = await response.json();
```

The data will be returned in the format described in the [FORMAT](https://developers.cloudflare.com/analytics/analytics-engine/sql-reference/statements/#json) section of the documentation, allowing you to extract meta information about the names and types of returned columns in addition to the data itself and a row count.

## Example Worker

The following is a sample Worker which executes a query against a dataset of weather readings and displays minimum and maximum values for each city.

### Environment variable setup

First the environment variables are set up with the account ID and API token.

The account ID is set in the [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/):

* [  wrangler.jsonc ](#tab-panel-6979)
* [  wrangler.toml ](#tab-panel-6980)

JSONC

```
{  "vars": {    "ACCOUNT_ID": "<account_id>"  }}
```

TOML

```
[vars]ACCOUNT_ID = "<account_id>"
```

The API\_TOKEN can be set as a secret, using the wrangler command line tool, by running the following and entering your token string:

Terminal window

```
npx wrangler secret put API_TOKEN
```

### Worker script

The worker script itself executes a query and formats the result:

JavaScript

```
export default {  async fetch(request, env) {    // This worker only responds to requests at the root.    if (new URL(request.url).pathname != "/") {      return new Response("Not found", { status: 404 });    }
    // SQL string to be executed.    const query = `            SELECT                blob1 AS city,                max(double1) as max_temp,                min(double1) as min_temp            FROM weather            WHERE timestamp > NOW() - INTERVAL '1' DAY            GROUP BY city            ORDER BY city`;
    // Build the API endpoint URL and make a POST request with the query string    const API = `https://api.cloudflare.com/client/v4/accounts/${env.ACCOUNT_ID}/analytics_engine/sql`;    const queryResponse = await fetch(API, {      method: "POST",      headers: {        Authorization: `Bearer ${env.API_TOKEN}`,      },      body: query,    });
    // The API will return a 200 status code if the query succeeded.    // In case of failure we log the error message and return a failure message.    if (queryResponse.status != 200) {      console.error("Error querying:", await queryResponse.text());      return new Response("An error occurred!", { status: 500 });    }
    // Read the JSON data from the query response and render the data as HTML.    const queryJSON = await queryResponse.json();    return new Response(renderResponse(queryJSON.data), {      headers: { "content-type": "text/html" },    });  },};
// renderCity renders a table row as HTML from a data row.function renderCity(row) {  return `<tr><td>${row.city}</td><td>${row.min_temp}</td><td>${row.max_temp}</td></tr>`;}
// renderResponse renders a simple HTML table of results.function renderResponse(data) {  return `<!DOCTYPE html><html>    <body>        <table>            <tr><th>City</th><th>Min Temp</th><th>Max Temp</th></tr>            ${data.map(renderCity).join("\n")}        </table>    </body><html>`;}
```

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