order, group, and join tables

use SQLAlchemy

pdm.lock

@@ -5,7 +5,7 @@
 groups = ["default"]
 strategy = ["cross_platform", "inherit_metadata"]
 lock_version = "4.4.1"
-content_hash = "sha256:2be337f3deba8cffea31cdbd43024c3db7bed53a688b484b32a3b92c27c530cf"
+content_hash = "sha256:3c4bf81bc71a0e1f56d0f71f725ba2668ff4346e236ae89f946e0ee388a47e83"
 
 [[package]]
 name = "asttokens"
@@ -42,6 +42,26 @@ files = [
     {file = "executing-2.0.1.tar.gz", hash = "sha256:35afe2ce3affba8ee97f2d69927fa823b08b472b7b994e36a52a964b93d16147"},
 ]
 
+[[package]]
+name = "greenlet"
+version = "3.0.3"
+requires_python = ">=3.7"
+summary = "Lightweight in-process concurrent programming"
+groups = ["default"]
+marker = "platform_machine == \"win32\" or platform_machine == \"WIN32\" or platform_machine == \"AMD64\" or platform_machine == \"amd64\" or platform_machine == \"x86_64\" or platform_machine == \"ppc64le\" or platform_machine == \"aarch64\""
+files = [
+    {file = "greenlet-3.0.3-cp312-cp312-macosx_11_0_universal2.whl", hash = "sha256:70fb482fdf2c707765ab5f0b6655e9cfcf3780d8d87355a063547b41177599be"},
+    {file = "greenlet-3.0.3-cp312-cp312-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:d4d1ac74f5c0c0524e4a24335350edad7e5f03b9532da7ea4d3c54d527784f2e"},
+    {file = "greenlet-3.0.3-cp312-cp312-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:149e94a2dd82d19838fe4b2259f1b6b9957d5ba1b25640d2380bea9c5df37676"},
+    {file = "greenlet-3.0.3-cp312-cp312-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:15d79dd26056573940fcb8c7413d84118086f2ec1a8acdfa854631084393efcc"},
+    {file = "greenlet-3.0.3-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:881b7db1ebff4ba09aaaeae6aa491daeb226c8150fc20e836ad00041bcb11230"},
+    {file = "greenlet-3.0.3-cp312-cp312-manylinux_2_24_x86_64.manylinux_2_28_x86_64.whl", hash = "sha256:fcd2469d6a2cf298f198f0487e0a5b1a47a42ca0fa4dfd1b6862c999f018ebbf"},
+    {file = "greenlet-3.0.3-cp312-cp312-musllinux_1_1_aarch64.whl", hash = "sha256:1f672519db1796ca0d8753f9e78ec02355e862d0998193038c7073045899f305"},
+    {file = "greenlet-3.0.3-cp312-cp312-musllinux_1_1_x86_64.whl", hash = "sha256:2516a9957eed41dd8f1ec0c604f1cdc86758b587d964668b5b196a9db5bfcde6"},
+    {file = "greenlet-3.0.3-cp312-cp312-win_amd64.whl", hash = "sha256:bba5387a6975598857d86de9eac14210a49d554a77eb8261cc68b7d082f78ce2"},
+    {file = "greenlet-3.0.3.tar.gz", hash = "sha256:43374442353259554ce33599da8b692d5aa96f8976d567d4badf263371fbe491"},
+]
+
 [[package]]
 name = "icecream"
 version = "2.1.3"
@@ -112,3 +132,37 @@ files = [
     {file = "six-1.16.0-py2.py3-none-any.whl", hash = "sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254"},
     {file = "six-1.16.0.tar.gz", hash = "sha256:1e61c37477a1626458e36f7b1d82aa5c9b094fa4802892072e49de9c60c4c926"},
 ]
+
+[[package]]
+name = "sqlalchemy"
+version = "2.0.30"
+requires_python = ">=3.7"
+summary = "Database Abstraction Library"
+groups = ["default"]
+dependencies = [
+    "greenlet!=0.4.17; platform_machine == \"win32\" or platform_machine == \"WIN32\" or platform_machine == \"AMD64\" or platform_machine == \"amd64\" or platform_machine == \"x86_64\" or platform_machine == \"ppc64le\" or platform_machine == \"aarch64\"",
+    "typing-extensions>=4.6.0",
+]
+files = [
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-macosx_10_9_x86_64.whl", hash = "sha256:5a79d65395ac5e6b0c2890935bad892eabb911c4aa8e8015067ddb37eea3d56c"},
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-macosx_11_0_arm64.whl", hash = "sha256:9a5baf9267b752390252889f0c802ea13b52dfee5e369527da229189b8bd592e"},
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:3cb5a646930c5123f8461f6468901573f334c2c63c795b9af350063a736d0134"},
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:296230899df0b77dec4eb799bcea6fbe39a43707ce7bb166519c97b583cfcab3"},
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-musllinux_1_1_aarch64.whl", hash = "sha256:c62d401223f468eb4da32627bffc0c78ed516b03bb8a34a58be54d618b74d472"},
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-musllinux_1_1_x86_64.whl", hash = "sha256:3b69e934f0f2b677ec111b4d83f92dc1a3210a779f69bf905273192cf4ed433e"},
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-win32.whl", hash = "sha256:77d2edb1f54aff37e3318f611637171e8ec71472f1fdc7348b41dcb226f93d90"},
+    {file = "SQLAlchemy-2.0.30-cp312-cp312-win_amd64.whl", hash = "sha256:b6c7ec2b1f4969fc19b65b7059ed00497e25f54069407a8701091beb69e591a5"},
+    {file = "SQLAlchemy-2.0.30-py3-none-any.whl", hash = "sha256:7108d569d3990c71e26a42f60474b4c02c8586c4681af5fd67e51a044fdea86a"},
+    {file = "SQLAlchemy-2.0.30.tar.gz", hash = "sha256:2b1708916730f4830bc69d6f49d37f7698b5bd7530aca7f04f785f8849e95255"},
+]
+
+[[package]]
+name = "typing-extensions"
+version = "4.12.1"
+requires_python = ">=3.8"
+summary = "Backported and Experimental Type Hints for Python 3.8+"
+groups = ["default"]
+files = [
+    {file = "typing_extensions-4.12.1-py3-none-any.whl", hash = "sha256:6024b58b69089e5a89c347397254e35f1bf02a907728ec7fee9bf0fe837d203a"},
+    {file = "typing_extensions-4.12.1.tar.gz", hash = "sha256:915f5e35ff76f56588223f15fdd5938f9a1cf9195c0de25130c627e4d597f6d1"},
+]

pyproject.toml

@@ -9,6 +9,7 @@ dependencies = [
     "psycopg2-binary>=2.9.9",
     "python-dotenv>=1.0.1",
     "icecream>=2.1.3",
+    "SQLAlchemy>=2.0.30",
 ]
 requires-python = ">=3.12"
 readme = "README.md"
@@ -19,7 +20,7 @@ requires = ["pdm-backend"]
 build-backend = "pdm.backend"
 
 [project.scripts]
-hello-postgres = "hello_postgres.__main__:main"
+datacamp-postgres-tutorial = "hello_postgres.datacamp_tutorial:main"
 
 
 [tool.pdm]

src/hello_postgres/datacamp_tutorial.py

@@ -1,6 +1,5 @@
-# https://www.freecodecamp.org/news/postgresql-in-python/
 # https://www.datacamp.com/tutorial/tutorial-postgresql-python
-# docker compose down && docker compose up -d && hello-postgres
+# docker compose down && docker compose up -d && datacamp-postgres-tutorial
 import psycopg2
 import dotenv
 import os 
@@ -8,6 +7,7 @@ import os
 
 
 def main():
+    dotenv.load_dotenv()
     print("Connecting to the PostgreSQL database...")
     conn = connect()
     cursor = conn.cursor()
@@ -45,13 +45,56 @@ def main():
     print("Deleting \"Introduction to Statistics in R\"...")
     cursor.execute("DELETE from datacamp_courses WHERE course_name = 'Introduction to Statistics in R';")
     conn.commit()
+    print("Sorting table by instructor...")
+    cursor.execute('SELECT * FROM datacamp_courses ORDER BY course_instructor')
+    rows = cursor.fetchall()
+    for row in rows:
+        print(row)
+    print("Fetching the number of courses each instructor teaches...")
+    cursor.execute('SELECT course_instructor, COUNT(*) FROM datacamp_courses GROUP BY course_instructor')
+    for row in cursor.fetchall():
+        print(row)
+    print("Creating the new table for language rankings...")
+    # https://www.w3schools.com/sql/sql_primarykey.ASP
+    cursor.execute("""
+    CREATE TABLE programming_languages (
+        language_id INT PRIMARY KEY,
+        language_name TEXT NOT NULL,
+        course_number INT NOT NULL,
+        tiobe_ranking INT NOT NULL
+    )
+""")
+    cursor.execute("""
+    INSERT INTO programming_languages (language_id, language_name, course_number, tiobe_ranking) 
+    VALUES 
+    (1, 'SQL', 31, 8),
+    (2, 'Python', 157, 1),
+    (3, 'R', 132, 16),
+    (4, 'Julia', 2, 33),
+    (5, 'Scala', 1, 38)
+""")
+    conn.commit()
+    # datacamp: "We will use an INNER JOIN to get only the information of the programming languages that appear in the datacamp_course table. "
+    print("Getting courses, their instructors, the topic, and the tiobe ranking of the language...")
+    cursor.execute("""SELECT course_name, course_instructor, topic, tiobe_ranking
+FROM datacamp_courses
+INNER JOIN programming_languages
+ON datacamp_courses.topic = programming_languages.language_name""")
+    for row in cursor.fetchall():
+        print(row)
     cursor.close()
     conn.close()
-    # cursor.execute("SELECT * FROM DB_table WHERE id = 1")
+    print("Now using SQLAlchemy to interact with the database...")
+    import sqlalchemy
+    engine = sqlalchemy.create_engine(f"postgresql://{os.getenv('POSTGRES_USER')}:{os.getenv('POSTGRES_PASSWORD')}@{os.getenv('DB_HOST')}:{os.getenv('DB_PORT')}/{os.getenv('POSTGRES_DB')}")
+    conn = engine.connect()
+    print("Fetching all the available rows...") 
+    output = conn.execute(sqlalchemy.text("SELECT * FROM datacamp_courses"))
+    print(output.fetchall())
+    conn.close()
 
 
 def connect():
-    dotenv.load_dotenv()
     conn = psycopg2.connect(
         database=os.getenv('POSTGRES_DB'),
         host=os.getenv('DB_HOST'),