---
title: Query a database
description: Query D1 using SQL statements through the Workers Binding API, REST API, or Wrangler commands.
image: https://edgetunnel-b2h.pages.dev/dev-products-preview.png
---

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# Query a database

D1 is compatible with most SQLite's SQL convention since it leverages SQLite's query engine. You can use SQL commands to query D1.

There are a number of ways you can interact with a D1 database:

1. Using [D1 Workers Binding API](https://edgetunnel-b2h.pages.dev/d1/worker-api/) in your code.
2. Using [D1 REST API](https://edgetunnel-b2h.pages.dev/api/resources/d1/subresources/database/methods/create/).
3. Using [D1 Wrangler commands](https://edgetunnel-b2h.pages.dev/d1/wrangler-commands/).

## Use SQL to query D1

D1 understands SQLite semantics, which allows you to query a database using SQL statements via Workers BindingAPI or REST API (including Wrangler commands). Refer to [D1 SQL API](https://edgetunnel-b2h.pages.dev/d1/sql-api/sql-statements/) to learn more about supported SQL statements.

### Use foreign key relationships

When using SQL with D1, you may wish to define and enforce foreign key constraints across tables in a database. Foreign key constraints allow you to enforce relationships across tables, or prevent you from deleting rows that reference rows in other tables. An example of a foreign key relationship is shown below.

```sql
CREATE TABLE users (
    user_id INTEGER PRIMARY KEY,
    email_address TEXT,
    name TEXT,
    metadata TEXT
)


CREATE TABLE orders (
    order_id INTEGER PRIMARY KEY,
    status INTEGER,
    item_desc TEXT,
    shipped_date INTEGER,
    user_who_ordered INTEGER,
    FOREIGN KEY(user_who_ordered) REFERENCES users(user_id)
)
```

Refer to [Define foreign keys](https://edgetunnel-b2h.pages.dev/d1/sql-api/foreign-keys/) for more information.

### Query JSON

D1 allows you to query and parse JSON data stored within a database. For example, you can extract a value inside a JSON object.

Given the following JSON object (`type:blob`) in a column named `sensor_reading`, you can extract values from it directly.

```json
{
    "measurement": {
        "temp_f": "77.4",
        "aqi": [21, 42, 58],
        "o3": [18, 500],
        "wind_mph": "13",
        "location": "US-NY"
    }
}
```

```sql
-- Extract the temperature value
SELECT json_extract(sensor_reading, '$.measurement.temp_f')-- returns "77.4" as TEXT
```

Refer to [Query JSON](https://edgetunnel-b2h.pages.dev/d1/sql-api/query-json/) to learn more about querying JSON objects.

## Query D1 with Workers Binding API

Workers Binding API primarily interacts with the data plane, and allows you to query your D1 database from your Worker.

This requires you to:

1. Bind your D1 database to your Worker.
2. Prepare a statement.
3. Run the statement.

**index.js**

```js
export default {
    async fetch(request, env) {
        const {pathname} = new URL(request.url);
        const companyName1 = `Bs Beverages`;
        const companyName2 = `Around the Horn`;
        const stmt = env.DB.prepare(`SELECT * FROM Customers WHERE CompanyName = ?`);


        if (pathname === `/RUN`) {
            const returnValue = await stmt.bind(companyName1).run();
            return Response.json(returnValue);
        }


        return new Response(
            `Welcome to the D1 API Playground!
            \nChange the URL to test the various methods inside your index.js file.`,
        );
    },
};
```

Refer to [Workers Binding API](https://edgetunnel-b2h.pages.dev/d1/worker-api/) for more information.

## Query D1 with REST API

REST API primarily interacts with the control plane, and allows you to create/manage your D1 database.

Refer to [D1 REST API](https://edgetunnel-b2h.pages.dev/api/resources/d1/subresources/database/methods/create/) for D1 REST API documentation.

## Query D1 with Wrangler commands

You can use Wrangler commands to query a D1 database. Note that Wrangler commands use REST APIs to perform its operations.

```sh
npx wrangler d1 execute prod-d1-tutorial --command="SELECT * FROM Customers"
```

```sh
🌀 Mapping SQL input into an array of statements
🌀 Executing on local database production-db-backend (<DATABASE_ID>) from .wrangler/state/v3/d1:
┌────────────┬─────────────────────┬───────────────────┐
│ CustomerId │ CompanyName         │ ContactName       │
├────────────┼─────────────────────┼───────────────────┤
│ 1          │ Alfreds Futterkiste │ Maria Anders      │
├────────────┼─────────────────────┼───────────────────┤
│ 4          │ Around the Horn     │ Thomas Hardy      │
├────────────┼─────────────────────┼───────────────────┤
│ 11         │ Bs Beverages        │ Victoria Ashworth │
├────────────┼─────────────────────┼───────────────────┤
│ 13         │ Bs Beverages        │ Random Name       │
└────────────┴─────────────────────┴───────────────────┘
```

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