> ## Documentation Index
> Fetch the complete documentation index at: https://auth0-docs-ia-custom-database-connections.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Delete User Database Action Script and Templates

> The Delete script runs when you need to delete a specified user from your external user store, and is required if you want to additionally delete the user from Auth0 in the same operation.

The Delete script implements the defined function to delete a specified user from an external database. We recommend naming this function `deleteUser`.

The script is only used in a [legacy authentication scenario](/docs/authenticate/database-connections/custom-db/overview-custom-db-connections), and is required if you want to delete a user from Auth0 and your external database in the same operation.

## DeleteUser function

The `deleteUser` function should:

* Remove the specified user from the external database.
* Return a `null` value if the deletion succeeded.
* Return an error if the deletion failed.

### Definition

The `deleteUser` function accepts two parameters and returns a `callback` function:

```js lines theme={null}
deleteUser(id, callback): function
```

| Parameter  | Type     | Description                                              |
| ---------- | -------- | -------------------------------------------------------- |
| `id`       | String   | User’s identity `user_id`. Does not start with `auth0`.  |
| `callback` | Function | Used to pass error or profile data through the pipeline. |

This is a pseudo-JavaScript example of how you could implement the `deleteUser` function:

```javascript lines theme={null}
function deleteUser(id, callback) {
  // Send user identifier to external database API
  let options = {
    url: "https://example.com/api/deleteUser",
    body: {
      id: id
    }
  };

  send(options, (err, profileData) => {
    // Return error in callback if deletion failed
    if (err) {
      return callback(new Error("My custom error message."));
    }

    // Return null value in callback if deletion succeeded
    return callback(null);
  });
}
```

## Callback function

The `callback` function accepts one parameter and returns a function.

### Definition

```js lines theme={null}
callback(error): function
```

| Parameter | Type   | Required | Description          |
| --------- | ------ | -------- | -------------------- |
| `error`   | Object | Required | Contains error data. |

### Return a success

If the user was successfully deleted in your external database, return the `callback` function, and pass a `null` value for the `error` parameter:

```js lines theme={null}
return callback(null);
```

### Return an error

If an error occurs, return the `callback` function, and pass relevant error information to the `error` parameter:

```js lines theme={null}
return callback(new Error("My custom error message."));
```

## Language-specific script examples

Auth0 provides sample scripts for use with the following languages/technologies:

<CodeGroup>
  ```javascript JavaScript lines theme={null}
  function remove (id, callback) {
    // This script remove a user from your existing database.
    // It is executed whenever a user is deleted from the Management API or Auth0 dashboard.
    //
    // There are two ways that this script can finish:
    // 1. The user was removed successfully:
    //     callback(null);
    // 2. Something went wrong while trying to reach your database:
    //     callback(new Error("my error message"));
    var msg = "Please implement the Delete script for this database " +
         "connection at https://manage.auth0.com/#/connections/database";
    return callback(new Error(msg));
  }
  ```

  ```javascript ASP.NET MVC3 lines expandable theme={null}
  // For ASP.NET Membership Provider (MVC3 - Universal Providers)
  function remove(id, callback) {
    const sqlserver = require('tedious@1.11.0');
    const Connection = sqlserver.Connection;
    const Request = sqlserver.Request;
    const TYPES = sqlserver.TYPES;
    const connection = new Connection({
      userName: 'the username',
      password: 'the password',
      server: 'the server',
      options: {
        database: 'the db name',
        encrypt: true,
        // Required to retrieve userId needed for Membership entity creation
        rowCollectionOnRequestCompletion: true
      }
    });
    connection.on('debug', function(text) {
      // if you have connection issues, uncomment this to get more detailed info
      // console.log(text);
    }).on('errorMessage', function(text) {
      // this will show any errors when connecting to the SQL database or with the SQL statements
      console.log(JSON.stringify(text));
    });
    connection.on('connect', function(err) {
      if (err) return callback(err);
      executeDelete(['Memberships', 'Users'], function(err) {
        if (err) return callback(err);
        callback(null);
      });
    });
    function executeDelete(tables, callback) {
      const query = tables.map(function(table) {
        return 'DELETE FROM ' + table + ' WHERE UserId = @UserId';
      }).join(';');
      const request = new Request(query, function(err) {
        if (err) return callback(err);
        callback(null);
      });
      request.addParameter('UserId', TYPES.VarChar, id);
      connection.execSql(request);
    }
  }
  ```

  ```javascript ASP.NET MVC4 lines expandable theme={null}
  // For ASP.NET Membership Provider (MVC4 - Simple Membership)
  function remove(id, callback) {
    const sqlserver = require('tedious@1.11.0');
    const Connection = sqlserver.Connection;
    const Request = sqlserver.Request;
    const TYPES = sqlserver.TYPES;
    const connection = new Connection({
      userName: 'the username',
      password: 'the password',
      server: 'the server',
      options: {
        database: 'the db name',
        encrypt: true,
        // Required to retrieve userId needed for Membership entity creation
        rowCollectionOnRequestCompletion: true
      }
    });
    connection.on('debug', function (text) {
      // if you have connection issues, uncomment this to get more detailed info
      // console.log(text);
    }).on('errorMessage', function (text) {
      // this will show any errors when connecting to the SQL database or with the SQL statements
      console.log(JSON.stringify(text));
    });
    connection.on('connect', function (err) {
      if (err) return callback(err);
      executeDelete(['webpages_Membership', 'UserProfile'], function (err) {
        if (err) return callback(err);
        callback(null);
      });
    });
    function executeDelete(tables, callback) {
      const query = tables.map(function (table) {
        return 'DELETE FROM ' + table + ' WHERE UserId = @UserId';
      }).join(';');
      const request = new Request(query, function (err) {
        if (err) return callback(err);
        callback(null);
      });
      request.addParameter('UserId', TYPES.VarChar, id);
      connection.execSql(request);
    }
  }
  ```

  ```javascript MongoDB lines theme={null}
  function remove(id, callback) {
    const MongoClient = require('mongodb@3.1.4').MongoClient;
    const client = new MongoClient('mongodb://user:pass@mymongoserver.com');
    client.connect(function (err) {
      if (err) return callback(err);
      const db = client.db('db-name');
      const users = db.collection('users');
      users.remove({ _id: id }, function (err) {
        client.close();
        if (err) return callback(err);
        callback(null);
      });
    });
  }
  ```

  ```javascript MySQL lines theme={null}
  function remove(id, callback) {
    const mysql = require('mysql');
    const connection = mysql({
      host: 'localhost',
      user: 'me',
      password: 'secret',
      database: 'mydb'
    });
    connection.connect();
    const query = 'DELETE FROM users WHERE id = ?';
    connection.query(query, [ id ], function(err) {
      if (err) return callback(err);
      callback(null);
    });
  }
  ```

  ```javascript PostgreSQL lines theme={null}
  function remove(id, callback) {
    //this example uses the "pg" library
    //more info here: https://github.com/brianc/node-postgres
    const postgres = require('pg');
    const conString = 'postgres://user:pass@localhost/mydb';
    postgres.connect(conString, function (err, client, done) {
      if (err) return callback(err);
      const query = 'DELETE FROM users WHERE id = $1';
      client.query(query, [id], function (err) {
        // NOTE: always call `done()` here to close
        // the connection to the database
        done();
        return callback(err);
      });
    });
  }
  ```

  ```javascript SQL Server lines expandable theme={null}
  function remove(id, callback) {
    // this example uses the "tedious" library
    // more info here: http://pekim.github.io/tedious/index.html
    const sqlserver = require('tedious@1.11.0');
    const Connection = sqlserver.Connection;
    const Request = sqlserver.Request;
    const TYPES = sqlserver.TYPES;
    const connection = new Connection({
      userName:  'test',
      password:  'test',
      server:    'localhost',
      options:  {
        database: 'mydb'
      }
    });
    const query = 'DELETE FROM dbo.Users WHERE id = @UserId';
    connection.on('debug', function (text) {
      console.log(text);
    }).on('errorMessage', function (text) {
      console.log(JSON.stringify(text, null, 2));
    }).on('infoMessage', function (text) {
      console.log(JSON.stringify(text, null, 2));
    });
    connection.on('connect', function (err) {
      if (err) return callback(err);
      const request = new Request(query, function (err) {
        if (err) return callback(err);
        callback(null);
      });
      request.addParameter('UserId', TYPES.VarChar, id);
      connection.execSql(request);
    });
  }
  ```

  ```javascript Azure SQL Database lines expandable theme={null}
  function remove (id, callback) {
    // this example uses the "tedious" library
    // more info here: http://pekim.github.io/tedious/index.html
    var Connection = require('tedious@1.11.0').Connection;
    var Request = require('tedious@1.11.0').Request;
    var TYPES = require('tedious@1.11.0').TYPES;
    var connection = new Connection({
      userName: 'your-user@your-server-id.database.windows.net',
      password: 'the-password',
      server: 'your-server-id.database.windows.net',
      options: {
        database: 'mydb',
        encrypt: true
      }
    });
    connection.on('debug', function (text) {
      console.log(text);
    }).on('errorMessage', function (text) {
      console.log(JSON.stringify(text, null, 2));
    }).on('infoMessage', function (text) {
      console.log(JSON.stringify(text, null, 2));
    });
    connection.on('connect', function (err) {
      if (err) { return callback(err); }
      var query = 'DELETE FROM users WHERE id = @UserId';
      var request = new Request(query, function (err) {
        if (err) { return callback(err); }
        callback(null);
      });
      request.addParameter('UserId', TYPES.VarChar, id);
      connection.execSql(request);
    });
  }
  ```
</CodeGroup>