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SQL Essentials for Quick Revision

🚀 SELECT
Retrieve data from one or more tables.

🎯 WHERE Clause
Filter records based on specific conditions.

🔄 ORDER BY
Sort query results in ascending (ASC) or descending (DESC) order.

📊 Aggregation Functions

MIN, MAX, AVG, COUNT: Summarize data.

Window Functions: Perform calculations across a dataset without grouping rows.


🔑 GROUP BY
Group data based on one or more columns and apply aggregate functions.

🔗 JOINS

INNER JOIN: Fetch matching rows from both tables.

LEFT JOIN: All rows from the left table and matching rows from the right.

RIGHT JOIN: All rows from the right table and matching rows from the left.

FULL JOIN: Combine rows when there is a match in either table.

SELF JOIN: Join a table with itself.


🧩 Common Table Expressions (CTE)
Simplify complex queries with temporary result sets.

Quick SQL Revision Notes 📌
Master these concepts for interviews and projects!

#SQL #DataEngineer #QuickNotes
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🚀 Master SQL for Data Engineer and Ace Interviews

To succeed as a Data Analyst, focus on these essential SQL topics:

1️⃣ Fundamental SQL Commands
SELECT, FROM, WHERE

GROUP BY, HAVING, LIMIT


2️⃣ Advanced Querying Techniques
Joins: LEFT, RIGHT, INNER, SELF, CROSS

Aggregate Functions: SUM(), MAX(), MIN(), AVG()

Window Functions: ROW_NUMBER(), RANK(), DENSE_RANK(), LEAD(), LAG(), SUM() OVER()

Conditional Logic & Pattern Matching:

CASE statements for conditions

LIKE for pattern matching


Complex Queries: Subqueries, Common Table Expressions (CTEs), temporary tables


3️⃣ Performance Tuning
Optimize queries for better performance

Learn indexing strategies


4️⃣ Practical Applications
Solve case studies from Ankit Bansal's YouTube channel

Watch 10-15 minute tutorials, practice along for hands-on learning


5️⃣ End-to-End Projects
Search "Data Analysis End-to-End Projects Using SQL" on YouTube

Practice the full process: data extraction ➡️ cleaning ➡️ analysis


6️⃣ Real-World Data Analysis
Analyze real datasets for insights

Practice cleaning, handling missing values, and dealing with outliers


7️⃣ Advanced Data Manipulation
Use advanced SQL functions for transforming raw data into insights

Practice combining data from multiple sources


8️⃣ Reporting & Dashboards
Build impactful reports and dashboards using SQL and Power BI


9️⃣ Interview Preparation
Practice common SQL interview questions

Solve exercises and coding challenges


🔑 Pro Tip: Hands-on practice is key! Apply these steps to real projects and datasets to strengthen your expertise and confidence.

#SQL #DataEngineer #CareerGrowth