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 #DataAnalytics #QuickNotes

The Secret to learn SQL:
It's not about knowing everything
It's about doing simple things well

What You ACTUALLY Need:

1. SELECT Mastery

* SELECT * LIMIT 10
(yes, for exploration only!)
* COUNT, SUM, AVG
(used every single day)
* Basic DATE functions
(life-saving for reports)
* CASE WHEN

2. JOIN Logic

* LEFT JOIN
(your best friend)
* INNER JOIN
(your second best friend)
* That's it.

3. WHERE Magic
* Basic conditions
* AND, OR operators
* IN, NOT IN
* NULL handling
* LIKE for text search

4. GROUP BY Essentials
* Basic grouping
* HAVING clause
* Multiple columns
* Simple aggregations

Most common tasks:
* Pull monthly sales
* Count unique customers
* Calculate basic metrics
* Filter date ranges
* Join 2-3 tables

Focus on:
* Clean code
* Clear comments
* Consistent formatting
* Proper indentation

Here you can find essential SQL Interview Resources👇
https://t.me/mysqldata

Like this post if you need more 👍❤️

Hope it helps :)

#sql