Database & SQL

Master SQL queries, joins, window functions, CTEs, and aggregations — increasingly tested in technical interviews and essential for every developer.

6 exercises

mediumSQL

Relational Division: Customers Who Ordered All Products in a Category

# Find Customers Who Ordered Every Product in a Category Write a SQL query that finds customers who have ordered **ever...

sqlrelational-divisionjoins+5

mediumSQL

Employee Salary Ranking with Window Functions

Write SQL queries using window functions to analyze employee salary data within departments. You have access to an `emp...

sqlwindow-functions

mediumSQL

Recursive CTE for Employee Manager Chain

Create a SQL query using Common Table Expressions (CTEs) to build a complete organizational hierarchy showing the chain...

sqlrecursive-cte

mediumSQL

Finding Highest-Paid Employee by Department

Write a SQL query that joins three tables to find the highest-paid employee in each department. You have three tables:...

sqljoins

easySQL

Finding High-Volume Customers

Write a SQL query to identify customers who have placed more than 3 orders. You'll work with two tables: - `customers`:...

sqljoins

easySQL

SQL Filtering and Ordering - Employee Query

Write a SQL query to find employees in the Engineering department who were hired after January 1st, 2023. ## Requiremen...

sqlfiltering