If the `db_name` database already exists, then ClickHouse doesn’t create a new database and:
- Doesn’t throw an exception if clause is specified.
- Throws an exception if clause isn’t specified.
### ON CLUSTER {#on-cluster}
ClickHouse creates the `db_name` database on all the servers of a specified cluster. More details in a [Distributed DDL](../../../sql-reference/distributed-ddl.md) article.
### ENGINE {#engine}
[MySQL](../../../engines/database-engines/mysql.md) allows you to retrieve data from the remote MySQL server. By default, ClickHouse uses its own [database engine](../../../engines/database-engines/index.md). There’s also a [lazy](../../../engines/database-engines/lazy.md) engine.