SQL

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Coding
Theory
Quiz

    Basic Select

    • High Protein and Low Carb Foods

      Junior

    • Member Referral

      Junior

    • GeoStats

      Junior

    • Post Views

      Junior

    • Invalid Posts

      Junior

    • Big Countries

      Junior

    • Distinct Payment Methods Query

      Junior

    • Find Orders with High Totals

      Junior

    • Incident Status Filter

      Junior

    • Low Quality Problems

      Junior

    • First and Last Records

      Junior

    • Names Starting With Letter and Minimum Length

      Junior

    • Overdue Rentals

      Junior

    • Threat Detection Log Filter

      Junior

    • Unfinished Parts

      Junior

    • Swap Salary

      Junior

    • Distinct Flight Routes

      Mid

    • Reformat Department Table

      Mid

    • Count Active Projects

      Mid

    • Swap Genders Query

      Mid

    • Subscriptions Expiring Within 7 Days

      Mid

    Basic Joins

    • Map Employee Codes to Unique Identifiers

      Junior

    • Product Purchase Analysis

      Junior

    • Visits Without Purchases

      Junior

    • Daily Temperature Increase

      Junior

    • Calculate Average Processing Duration per Machine

      Junior

    • Report Employee Incentives

      Junior

    • Track Student Exam Participation

      Junior

    • Battery Efficiency

      Junior

    • Cartesian Product Analysis

      Junior

    • Employee Bonus

      Junior

    • Employees Earning More Than Managers

      Junior

    • Product and Supplier Join

      Junior

    • Rising Temperature

      Junior

    • Unreviewed Products

      Junior

    • Weather Type in Each Country

      Junior

    • Top Travellers

      Junior

    • Identify Managers with Multiple Direct Reports

      Mid

    • User Confirmation Success Rate

      Mid

    • Average Deal Size by Segment

      Mid

    • Average Storage Usage per User

      Mid

    • Client Session Duration Report

      Mid

    • Complex Joins for Incident Reporting

      Mid

    • Employee Department Join

      Mid

    • Department Highest Salary

      Mid

    • File System Metadata Query

      Mid

    • Active Customers with Order Count

      Mid

    • Promotional Campaign Analysis

      Mid

    • Multi-Table Join HR Report

      Mid

    • Ride-Sharing Trip Summary

      Mid

    • Orders with Product Details

      Mid

    • Real-Time Dasher Tracking & GPS History

      Mid

    • Vehicle Service Center Management

      Mid

    • Combine Two Tables

      Mid

    • Total Sales Per Region by Product Category

      Mid

    • Trip and Payment Schema Linking

      Mid

    • Whale User Identification

      Mid

    • Costco Item Spending by 2022 Registered Users

      Mid

    • Purchases Before Ban

      Mid

    Basic Aggregate Functions

    • Select Non-Boring Films

      Junior

    • Calculate Average Product Cost

      Junior

    • Average Employee Experience per Project

      Junior

    • Calculate Contest Participation Rates

      Junior

    • Analyze Search Performance

      Junior

    • Average Driver Rating per City

      Junior

    • Average Items per Order

      Junior

    • Average Power Consumption

      Junior

    • Average Transaction Amount

      Junior

    • Commute Time Analysis

      Junior

    • Managers with at Least 5 Direct Reports

      Junior

    • Customer Placed the Largest Number of Orders

      Junior

    • Daily Log Volume

      Junior

    • Department-wise Employee Count

      Junior

    • Final Account Balance

      Junior

    • iCloud Storage Analysis Query

      Junior

    • Immediate Food Delivery I

      Junior

    • Inventory Multi-Column Grouping

      Junior

    • Users With Multiple Tags

      Junior

    • Protocol Traffic Analysis

      Junior

    • Merchant Performance Analysis

      Junior

    • New Signups by Country

      Junior

    • QuickBooks vs. TurboTax Filing Count

      Junior

    • Monthly Revenue & Customer Aggregation

      Junior

    • SQL First Login Time Per User

      Junior

    • SQL Monthly Payroll Reporting

      Junior

    • Friend Requests I: Overall Acceptance Rate

      Junior

    • Monthly Transaction Summary

      Mid

    • Percentage of Same-Day First Orders

      Mid

    • Player Consecutive Login Analysis

      Mid

    • IoT Traffic Monitoring

      Mid

    • Top N Transactions

      Mid

    • Average Time of Process per Machine

      Mid

    • Average Product Ratings per Month

      Mid

    • Average Ticket Resolve Time

      Mid

    • Merge Request Activity Summary

      Mid

    • Data Ingestion Trends

      Mid

    • Game Play Analysis III

      Mid

    • Duplicate File Upload Detection

      Mid

    • First and Last Activity

      Mid

    • Order Processing Efficiency

      Mid

    • Monthly Average Sales Analysis

      Mid

    • Monthly Traffic Usage Analysis per Customer

      Mid

    • Average Stream Duration Per User by Topic

      Mid

    • New Product Launches

      Mid

    • Peak Hour Earnings Query

      Mid

    • Power User Identification

      Mid

    • Sending vs. Opening Snaps

      Mid

    • Blocked IPs - Top 10 Source IPs

      Mid

    • Subreddit Activity Reporting

      Mid

    • Team Scores in Football Tournament

      Mid

    • Ticket Resolution Latency

      Mid

    • Top Contributors by Write Actions

      Mid

    • Account Balance After Transfers

      Mid

    • Monthly Active Users

      Mid

    • Monthly Revenue per Merchant

      Mid

    • Top Subreddits by Activity

      Mid

    • Peak Sales Hour

      Mid

    • Vehicle Bridge-Crossing Tracker

      Mid

    • Top Engaged Users by Interaction

      Mid

    • Primary vs. Other Address

      Mid

    • User Engagement Metrics

      Mid

    • Top Storage Consuming Users

      Mid

    • Unified System View

      Mid

    • User Activity for the Past 30 Days I

      Mid

    • Active User Query

      Mid

    • Aggregation over Dataset Metadata

      Mid

    • Bridge Checkpoint Analysis

      Mid

    • Average Completion Time

      Mid

    • Connection Statistics

      Mid

    • Average Employee Leave

      Mid

    • Calculate Call Duration

      Mid

    • Customer Order Filtering

      Mid

    • Customer Order Analysis

      Mid

    • Driver Rating Analysis

      Mid

    • Frequent Transactors

      Mid

    • Identify High Spenders

      Mid

    • Monthly Issuance Difference

      Mid

    • Monthly Usage Summary

      Mid

    • Monthly Transaction Analysis

      Mid

    • Trade Volume Aggregation

      Mid

    • Recent Order Aggregation

      Mid

    • Task Completion Analytics

      Mid

    • User Spend Analysis

      Mid

    • Find VIP Loan Users

      Mid

    • Average Customer Query by City

      Mid

    • SQL Marks Threshold Query

      Mid

    • Top 3 Most Ordered Food Items

      Mid

    • Email Click-Through-Rate (CTR)

      Senior

    • Double-Entry Ledger

      Senior

    • Monthly Revenue Pivot Query

      Senior

    • Ledger Reconciliation

      Senior

    • Immediate Food Delivery II

      Senior

    • Friend Requests II: Who Has the Most Friends

      Senior

    • Customer Transaction Analysis

      Senior

    Sorting & Grouping

    • Count Unique Courses Taught by Each Instructor

      Junior

    • Daily User Engagement Over 30 Days

      Junior

    • Classes With Minimum Enrollment

      Junior

    • Count User Followers

      Junior

    • Find Largest Unique Value

      Junior

    • Group Transactions by Item

      Junior

    • Product First Sale Analysis

      Mid

    • Find Customers Who Purchased All Items

      Mid

    • Rank Scores

      Mid

    • Artist Popularity Rank

      Mid

    • Average Login Interval

      Mid

    • Daily Final Transaction

      Mid

    • First Touch Attribution

      Mid

    • Nth Transaction of Every User

      Mid

    • Merchant Revenue Analysis

      Mid

    • Oscar Nominee Leaderboard

      Mid

    • Sales Volume Growth

      Mid

    • Identify Power Users

      Mid

    • Top 3 Categories by Total Revenue

      Mid

    • Average Transaction Rank

      Mid

    • Capital Gain/Loss

      Mid

    • Top Rated Products

      Mid

    • Top K Customers by Spend

      Mid

    • Top Merchants by Spend

      Mid

    • Top Repository Contributors

      Mid

    • User Session Activity

      Mid

    • Whale Customers

      Mid

    • Running Total of Cyber Threats per Client

      Mid

    • Remove Duplicates without DISTINCT

      Mid

    • Monthly Growth Report

      Mid

    • Sales Leaderboard

      Mid

    • Running Total of Sales

      Mid

    • Top N Categories

      Mid

    • Top 3 Customers by Transaction Volume (Last 30 Days)

      Mid

    • Top Spenders Per Region With No Recent Activity

      Senior

    Advanced Select & Joins

    • Manager Reporting Structure

      Junior

    • Determine Primary Department for Employees

      Junior

    • Determine Valid Triangles

      Junior

    • Find Consecutive Values

      Mid

    • Product Price History

      Mid

    • Last Passenger to Board the Shuttle

      Mid

    • Count Income Categories

      Mid

    • Course and Student Management System

      Mid

    • Delete Duplicate Emails

      Mid

    • Duplicate Detection

      Mid

    • Find Discrepancies (Reconciliation)

      Mid

    • Local Stock Maxima

      Mid

    • Premium Users Exceeding Usage Limit

      Mid

    • Inventory Deductions

      Mid

    • Parking Garage System

      Mid

    • Permission System Access Report

      Mid

    • Moving Average of Daily Active Users

      Mid

    • Find Overlapping Bookings

      Mid

    • Optimistic Locking Implementation

      Mid

    • Overlapping Subscriptions

      Mid

    • Historical Address Tracking

      Mid

    • Product Review System

      Mid

    • Least Efficient Driver

      Mid

    • Real-Time Chat Message Retrieval

      Mid

    • Repeated Payment Detection

      Mid

    • Many-to-Many Labeling System

      Mid

    • Subscription Service Pro-Rated Billing

      Mid

    • Managers Earning Less Than Subordinates

      Mid

    • Moving Average of Transaction Volumes

      Mid

    • SQL Join with Duplicate Values

      Mid

    • Unique Transfer Relationships

      Mid

    • Transaction Reconciliation

      Mid

    • Project-Specific Numbering (ID vs. IID)

      Mid

    • Restaurant Growth

      Mid

    • Threaded Replies

      Mid

    • Employee-Manager Hierarchy

      Mid

    • Employee Management Chain

      Mid

    • Stock Volume Variation Trend

      Mid

    • Top Friends

      Mid

    • Deduplicate Activity Logs

      Mid

    • Finding Distinct Communicators

      Mid

    • First Share & Closest Collaborator

      Mid

    • Revoked Postings

      Mid

    • Project Budget Analysis

      Mid

    • Top Selling Shops

      Mid

    • Generate Shopping List from Recipes

      Mid

    • Evaluate Boolean Expression

      Mid

    • Game Play Analysis V

      Senior

    • Consecutive Trading Days

      Senior

    • E-Commerce Database Schema Design

      Senior

    • Dating App Mutual Matches

      Senior

    • Delivery Latency Query

      Senior

    • End-to-End Dasher Payouts

      Senior

    • Identify High-Velocity Cards

      Senior

    • Design Product Catalog

      Senior

    • NFT Minter with Metadata Schema

      Senior

    • Median Employee Salary

      Senior

    • Overlapping and Disjoint Meetings

      Senior

    • Find Cumulative Salary of an Employee

      Senior

    • Real-Time Satellite Image Metadata Store

      Senior

    • Notification Delivery Summary

      Senior

    • Friend Recommendation Query

      Senior

    • Pessimistic Locking - Account Transfer

      Senior

    • Splitwise Expense Tracker

      Senior

    • User Activity Report

      Senior

    • Retention Cohorts

      Senior

    • Running Sales Since Restock

      Senior

    • Merchant Settlement Balance

      Senior

    • Transaction Management System

      Senior

    • Trips and Users

      Senior

    • Optimize a Slow Search Query

      Senior

    • Temporary Email Service with TTL

      Senior

    • User Concurrent Sessions

      Senior

    • Overlapping Time Slots

      Senior

    • Time-Series Ledger - Latest Crypto Price

      Senior

    • Slow Merchant Transactions Query

      Senior

    • Report Contiguous Dates

      Senior

    • Find Gaps in Sequential IDs

      Senior

    • Top Categories and Active Users

      Senior

    • User Engagement Query

      Senior

    • User Session Analysis

      Senior

    • Consecutive Numbers

      Senior

    • Restaurant Churn Risk

      Senior

    • Customers with Purchases in 3 Consecutive Months

      Senior

    • Tournament Winners

      Senior

    Subqueries

    • Employees with Departed Managers

      Junior

    • Customers Who Never Order

      Junior

    • Find Missing Product IDs

      Junior

    • Swap Student Positions

      Mid

    • Movie Review Analysis

      Mid

    • Restaurant Revenue Analysis

      Mid

    • Find Users with the Most Connections

      Mid

    • Calculate Total Policy Values for 2025

      Mid

    • Restaurant Growth

      Mid

    • First 50% of Records

      Mid

    • Latest Transaction per User

      Mid

    • Identify Most Purchased Products

      Mid

    • Slow Shipping Duration Identification

      Mid

    • Stock Price Extremes

      Mid

    • Photoshop Revenue Analysis

      Mid

    • Soft Delete Query on Insert-Only Table

      Mid

    • Cohort Retention

      Mid

    • Find Duplicate Records

      Mid

    • Latest Version by Timestamp

      Mid

    • Job Posting Analytics

      Mid

    • Employee Tenure and Review

      Mid

    • Department Top Earners

      Senior

    • Complete Album Listeners

      Senior

    • Department Top Three Salaries

      Senior

    • Data Inconsistency and Missing Values Backfill

      Senior

    Advanced String Functions (Regex / Clause)

    • Standardize User Names

      Junior

    • Identify Patients with Type I Diabetes

      Junior

    • Find Second Highest Employee Wage

      Junior

    • JSON Data Extraction

      Mid

    • Skill Filtering

      Mid