Data Analytics

JOINS in SQL Joins allow you to combine data from multiple tables based on related columns. They are essential for working with relational databases. 1️⃣ Types of JOINS INNER JOIN → Returns only matching rows from both tables LEFT JOIN → Returns all rows…

GROUP BY & HAVING in SQL The GROUP BY clause is used to group rows that have the same values in specified columns. It’s commonly used with aggregation functions (SUM(), AVG(), COUNT(), etc.) to perform calculations on each group. The HAVING clause filters…

Aggregation Functions in SQL Aggregation functions help summarize data by performing calculations like sum, average, count, and more. These functions are commonly used in data analysis. 1️⃣ Common Aggregation Functions COUNT() → Counts the number of rows…

SQL Interview Questions with detailed answers 1️⃣9️⃣ How do you calculate the percentage of total sales for each category? To calculate the percentage of total sales for each category, we use SUM() and window functions or subqueries. Using Window Functions…

SQL Interview Questions with detailed answers 1️⃣8️⃣ Write an SQL query to find customers who have placed more than 3 orders. To find customers who have placed more than 3 orders, we can use the GROUP BY and HAVING clauses to count the number of orders…

Topic 2: Filtering & Advanced WHERE Clause in SQL Filtering data efficiently is crucial in data analysis. The WHERE clause helps filter rows based on conditions. Let’s explore some advanced filtering techniques. 1️⃣ Using Comparison Operators in WHERE Clause…

SQL Interview Questions with detailed answers 1️⃣7️⃣ What is indexing in SQL, and how does it improve performance? An index in SQL is a data structure that improves query performance by allowing faster data retrieval. It works like an index in a book, helping…