A database system is a system which consists of database repositories and DBMS software packages.
A DBMS, implemented in a specific database model, has SQL processor, optimizer and management, Lock management, Transaction management,
Network management, Security management, Storage management, Index management, etc.
A database repository is a storage which can be indexed in various indexing mechanisms.
Database models are
Hierarchical Database Model
Network Database Model
Relational Database Model
Object-oriented Database Model
Object-Relational Database Model
XML Database Model
Non-traditional Database Model
etc.
Relational Database Model has the concepts of
Relations, Attributes
Constraints and Integrity
Database schema
Structured Query Language (aka. Declarative Language)
SQL-embedded Host Language (aka. Procedural Language)
A template of SQL expressions
SELECT
FROM
WHERE
With this SQL template and its extended expressions,
how they can be embedded in a Python expression?
The advantages of embedding SQL expressions in a Python statement include
Automatic
Procedural execution of non-procedural SQL expressions