✨ Add (module): SQLAlchemy core example

Author: jpcadena

introduction/sa_core.py

@@ -0,0 +1,92 @@
+"""
+This module demonstrates the use of SQLAlchemy's Core functionality for
+ building and executing database queries.
+The example shows how to define table schemas and perform queries using the
+ SQLAlchemy Core expression language.
+It provides functionality to query books based on author names from a
+ structured database.
+"""
+
+from typing import Any, Sequence
+
+from sqlalchemy import (
+    Column,
+    Engine,
+    ForeignKey,
+    Integer,
+    MetaData,
+    Row,
+    Select,
+    String,
+    Table,
+    create_engine,
+    select,
+)
+
+engine: Engine = create_engine(
+    "mysql+pymysql://user:password@server/database",
+)
+metadata: MetaData = MetaData()
+authors: Table = Table(
+    "authors",
+    metadata,
+    Column(
+        "id",
+        Integer,
+        primary_key=True,
+    ),
+    Column(
+        "name",
+        String,
+    ),
+)
+books: Table = Table(
+    "books",
+    metadata,
+    Column(
+        "id",
+        Integer,
+        primary_key=True,
+    ),
+    Column(
+        "title",
+        String,
+    ),
+    Column(
+        "author_id",
+        Integer,
+        ForeignKey("authors.id"),
+    ),
+    Column(
+        "year",
+        Integer,
+    ),
+)
+
+
+def fetch_books_by_author(
+    author_name: str,
+) -> Sequence[Row[Any]]:
+    """
+    Retrieves all books written by the specified author.
+    :param author_name: The name of the author whose books to find.
+    :type author_name: str
+    :return: A list of all books from the given author name
+    :rtype: Sequence[Row[Any]]
+    """
+    select_statement: Select[Any] = (
+        select([books.c.title, books.c.year])  # type: ignore
+        .select_from(books.join(authors))
+        .where(authors.c.name == author_name)
+    )
+    with engine.connect() as connection:
+        return connection.execute(
+            select_statement,
+        ).fetchall()
+
+
+books_by_author: list[Row[Table]] = list(  # type: ignore
+    fetch_books_by_author("Gabriel García Márquez")
+)
+for book in books_by_author:
+    print(book)