ETL Guide ⚙️📊

1. What is ETL?

ETL is a process used to collect data from sources, clean/transform it, and load it into a database or data warehouse.

2. ETL Steps

Extract → Get data (CSV, API, DB)
Transform → Clean & process
Load → Store in database

3. Extract (Python)

import pandas as pd

df = pd.read_csv("data.csv")

4. Transform

df.dropna(inplace=True)
df["salary"] = df["salary"] * 1.1

5. Load (SQL)

import sqlite3

conn = sqlite3.connect("data.db")
df.to_sql("table", conn)

6. ETL Tools

- Apache Airflow
- Talend
- Informatica
- AWS Glue

7. Data Pipeline

Source → ETL → Database → Dashboard

8. Real Use Cases

• Data warehousing 📊
• Business analytics 💼
• Real-time pipelines ⚡
• ML data preparation 🤖