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
🚀 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