refactor: restructure monorepo for clean portfolio layout

- Move timesfm-forecast into apps/ directory
- Flatten Udacity portfolio projects from deep URL-encoded paths
  into data-engineering/01-XX numbered directories
- Remove old My-Data-Engineering-Portifolio/ parent directory
- Rewrite root README.md: professional overview with badges,
  project table, and repo structure diagram
- Create data-engineering/README.md with per-project descriptions
- Add README.md for 02-cassandra-modeling (was missing)
- Add README.md for 05-airflow-pipelines (was missing)
- Normalize capstone readme.md -> README.md
- Update .gitignore: add *.cfg, *.env, *.zip, *.sas7bdat,
  Jupyter checkpoints, IDE dirs; remove uv.lock exclusion
- Add dwh.cfg.example and dl.cfg.example credential templates
- Untrack real credential files (dwh.cfg, dl.cfg)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

data-engineering/01-postgres-modeling/sql_queries.py

@@ -0,0 +1,104 @@
+# DROP TABLES
+
+songplay_table_drop = "DROP TABLE IF EXISTS songplays;"
+user_table_drop = "DROP TABLE IF EXISTS users;"
+song_table_drop = "DROP TABLE IF EXISTS songs;"
+artist_table_drop = "DROP TABLE IF EXISTS artists;"
+time_table_drop = "DROP TABLE IF EXISTS time;"
+
+# CREATE TABLES
+
+songplay_table_create = ("""
+CREATE TABLE songplays (songplay_id SERIAL PRIMARY KEY NOT NULL
+, start_time timestamp NOT NULL
+, user_id int NOT NULL
+, level varchar NULL
+, song_id varchar NOT NULL
+, artist_id varchar NOT NULL
+, session_id int NOT NULL
+, location varchar NULL
+, user_agent varchar NULL);
+""")
+
+user_table_create = ("""
+CREATE TABLE users (user_id int PRIMARY KEY NOT NULL
+, first_name varchar NULL
+, last_name varchar NULL
+, gender varchar NULL
+, level varchar NULL);
+""")
+
+song_table_create = ("""
+CREATE TABLE songs (song_id varchar PRIMARY KEY UNIQUE NOT NULL
+, title varchar NOT NULL
+, artist_id varchar NULL
+, year int NULL
+, duration float NOT NULL);
+""")
+
+artist_table_create = ("""
+CREATE TABLE artists (artist_id varchar PRIMARY KEY UNIQUE NOT NULL
+, name varchar NOT NULL
+, location varchar NULL
+, latitude float NULL
+, longitude float NULL);
+""")
+
+time_table_create = ("""
+CREATE TABLE time (start_time timestamp NOT NULL
+, hour int NULL
+, day int NULL
+, week int NULL
+, month int NULL
+, year int NULL
+, weekday int NULL);
+""")
+
+# INSERT RECORDS
+
+songplay_table_insert = ("""
+INSERT INTO songplays (songplay_id, start_time, user_id, level, song_id, artist_id, session_id, location, user_agent) VALUES (%s,%s,%s,%s,%s,%s,%s,%s,%s)
+ON CONFLICT (songplay_id) DO NOTHING;
+""")
+
+user_table_insert = ("""
+INSERT INTO users (user_id, first_name, last_name, gender, level) VALUES (%s,%s,%s,%s,%s)
+ON CONFLICT (user_id) DO UPDATE SET
+level = EXCLUDED.level;
+""")
+
+song_table_insert = ("""
+INSERT INTO songs (song_id, title, artist_id, year, duration) VALUES (%s,%s,%s,%s,%s)
+ON CONFLICT (song_id) DO NOTHING;
+""")
+
+artist_table_insert = ("""
+INSERT INTO artists (artist_id, name, location, latitude, longitude) VALUES (%s,%s,%s,%s,%s)
+ON CONFLICT (artist_id) DO UPDATE SET
+location = EXCLUDED.location,
+latitude = EXCLUDED.latitude,
+longitude = EXCLUDED.longitude;
+""")
+
+
+time_table_insert = ("""
+INSERT INTO time (start_time, hour, day, week, month, year, weekday) VALUES (%s,%s,%s,%s,%s,%s,%s);
+""")
+
+# FIND SONGS
+# Implement the song_select query in sql_queries.py to find the song ID and artist ID based on the title, artist name, and duration of a song.
+# get songid and artistid from song and artist tables
+song_select = ("""
+SELECT s.song_id, a.artist_id 
+FROM songs AS s
+LEFT JOIN artists AS a 
+ON s.artist_id=a.artist_id
+WHERE s.title = (%s) AND \
+      a.name = (%s) AND \
+      s.duration = (%s);
+""")
+
+# QUERY LISTS
+
+create_table_queries = [songplay_table_create, user_table_create, song_table_create, artist_table_create, time_table_create]
+drop_table_queries = [songplay_table_drop, user_table_drop, song_table_drop, artist_table_drop, time_table_drop]