# oracle will feed host/port/SID into cx_oracle.makedsn
oracle_db = create_engine('oracle://scott:tiger@127.0.0.1:1521/sidname')
+ # mssql
+ mssql_db = create_engine('mssql://username:password@localhost/database')
+
+ # mssql via a DSN connection
+ mssql_db = create_engine('mssql://username:password@/?dsn=mydsn')
+
The `Engine` will ask the connection pool for a connection when the `connect()` or `execute()` methods are called. The default connection pool, `QueuePool`, as well as the default connection pool used with SQLite, `SingletonThreadPool`, will open connections to the database on an as-needed basis. As concurrent statements are executed, `QueuePool` will grow its pool of connections to a default size of five, and will allow a default "overflow" of ten. Since the `Engine` is essentially "home base" for the connection pool, it follows that you should keep a single `Engine` per database established within an application, rather than creating a new one for each connection.
#### Custom DBAPI connect() arguments