Python can handle many different types of databases. For each of these types a different API exists. So encourage similarity between those different API's, PEP 249 has been introduced.
This API has been defined to encourage similarity between the Python modules that are used to access databases. By doing this, we hope to achieve a consistency leading to more easily understood modules, code that is generally more portable across databases, and a broader reach of database connectivity from Python. PEP-249