[Home](./index.md) > [@firebase/database](./database.md) > [getDatabase](./database.getdatabase.md) ## getDatabase() function Returns the instance of the Realtime Database SDK that is associated with the provided [FirebaseApp](./app.firebaseapp.md). Initializes a new instance with with default settings if no instance exists or if the existing instance uses a custom database URL. Signature: ```typescript export declare function getDatabase(app?: FirebaseApp, url?: string): FirebaseDatabase; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | app | FirebaseApp | The [FirebaseApp](./app.firebaseapp.md) instance that the returned Realtime Database instance is associated with. | | url | string | The URL of the Realtime Database instance to connect to. If not provided, the SDK connects to the default instance of the Firebase App. | Returns: [FirebaseDatabase](./database.firebasedatabase.md) The `FirebaseDatabase` instance of the provided app.