The DatabaseManager¶
DatabaseManager is the base class that defines the interface of how to interact with
the database and provides the methods to do so. Each SQL dialect will inherit from the DatabaseManager
and define the specific details of how to connect to the database and create the database engine.
The database engine is the core component that allows for connection and interaction with the database.
The engine is created through the sqlalchemy.create_engine() function. The creation of the
connection string needed to create the engine is all handled during the initialization of an
instance of DatabaseManager. This class is never used on its own instead it serves as the facilitator
of functionality for each database dialect.
Database dialects¶
This section describes the available database dialects in Pandemy and the dialects planned for future releases.
SQLite:
SQLiteDb.Oracle: Planned.
Microsoft SQL Server: Planned.
Core functionality¶
All database dialects inherit these methods from DatabaseManager:
delete_all_records_from_table(): Delete all records from an existing table in the database.execute(): Execute arbitrary SQL statements on the database.load_table(): Load a table by name or SQL query into apandas.DataFrame.save_df(): Save apandas.DataFrameto a table in the database.
Examples of using these methods are shown in the SQLite section, but they work the same regardless of the SQL dialect used.
The SQLContainer¶
When initializing a subclass of DatabaseManager it can optionally be passed a SQLContainer
class to the container parameter. The purpose of the SQLContainer is to store SQL statements used by an application in one
place where they can be easily accessed by the DatabaseManager. Just like the DatabaseManager
the SQLContainer should be subclassed and not used directly. If your application supports multiple SQL databases you can
write the SQL statements the application needs in each SQL dialect and store the statements in one SQLContainer per dialect.
Examples of using the SQLContainer with the SQLite DatabaseManager SQLiteDb are shown in section
Using the SQLContainer.