When you want to connect to a database in SQLAlchemy, you need a connection string. It usually has the form
dialect[+driver]://user:[email protected]/dbname[?key=value..]
Quite often, the user is root and the host is localhost.
Once you have the valid connection string, you can test if it works via this script:
import sqlalchemy
engine = sqlalchemy.create_engine(SQLALCHEMY_DATABASE_URI, echo=True)
print(engine.table_names())
SQLite
requirements.txt: None
Connection:
SQLALCHEMY_DATABASE_URI = "sqlite:///absolute_filepath"
# Example:
SQLALCHEMY_DATABASE_URI = "sqlite:////tmp/test.db"
The first two slashes come from the seperator of dialect and driver, the third one from the separation between credentials+host and dbname, the fourth one is the path which is kind of the name of the database.
If you want an in-memory SQLite DB, just specify an empty URL (source):
SQLALCHEMY_DATABASE_URI = "sqlite://"
MySQL and MariaDB
requirements.txt:
PyMySQL
Connection:
SQLALCHEMY_DATABASE_URI = "mysql+pymysql://user:[email protected]/dbname"
There are a lot of other MySQL drivers:
mysqldb: C extension; does not work with Python 3 (reasons for pymysql)mysqlconnector: Officially provided by MySQL; worst performance and not downloadable via PyPI (source)
Others
I haven't tried it, but sqlalchemy lists more like Oracle, Microsoft SQL Server and Sybase.