# SELECT Select the Redis logical database having the specified zero-based numeric index. New connections always use the database 0. Selectable Redis databases are a form of namespacing: all databases are still persisted in the same RDB / AOF file. However different databases can have keys with the same name, and commands like [`FLUSHDB`](https://redis.io/docs/latest/commands/flushdb), [`SWAPDB`](https://redis.io/docs/latest/commands/swapdb) or [`RANDOMKEY`](https://redis.io/docs/latest/commands/randomkey) work on specific databases. In practical terms, Redis databases should be used to separate different keys belonging to the same application (if needed), and not to use a single Redis instance for multiple unrelated applications. When using Redis Cluster, the `SELECT` command cannot be used, since Redis Cluster only supports database zero. In the case of a Redis Cluster, having multiple databases would be useless and an unnecessary source of complexity. Commands operating atomically on a single database would not be possible with the Redis Cluster design and goals. Since the currently selected database is a property of the connection, clients should track the currently selected database and re-select it on reconnection. While there is no command in order to query the selected database in the current connection, the [`CLIENT LIST`](https://redis.io/docs/latest/commands/client-list) output shows, for each client, the currently selected database. ## Return information {{< multitabs id="select-return-info" tab1="RESP2" tab2="RESP3" >}} [Simple string reply](../../develop/reference/protocol-spec#simple-strings): `OK`. -tab-sep- [Simple string reply](../../develop/reference/protocol-spec#simple-strings): `OK`.