non_solid_etl.py

import pandas as pd
import sqlite3
import psycopg2
import pandas.io.sql as sqlio
import mysql.connector
import pymongo

def extract_from_excel(excel_file):
    return pd.read_excel(excel_file)

def extract_from_postgresql(db_name, query):
    conn = psycopg2.connect(database=db_name, user='username', password='password')
    return sqlio.read_sql_query(query, conn)

def extract_from_mysql(db_name, query):
    conn = mysql.connector.connect(database=db_name, user='username', password='password')
    cursor = conn.cursor()
    cursor.execute(query)
    result = cursor.fetchall()
    return pd.DataFrame(result)

def extract_from_mongodb(db_name, collection_name):
    client = pymongo.MongoClient("mongodb://localhost:27017/")
    db = client[db_name]
    collection = db[collection_name]
    return pd.DataFrame(list(collection.find()))

def transform(data):
    data['new_column'] = data['old_column'] * 2
    return data

def transform_and_replace_null(data, default_value):
    data = data.fillna(default_value)
    data['new_column'] = data['old_column'] * 2
    return data

def load_to_sql(data, db_name):
    conn = sqlite3.connect(db_name)
    data.to_sql('table_name', conn)

def load_to_s3(data, bucket_name, file_name):
    data.to_csv(file_name)
    s3.upload_file(file_name, bucket_name, file_name)

data = extract_from_mongodb('database_name', 'collection_name')
data = transform_and_replace_null(data, 0)
load_to_s3(data, 'bucket_name', 'file_name.csv')