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Top-Level Pages
- Home
- About
- Quiz
- Tutorials
- SQL Playground
- SQL Practice
- Help
- Contact
- Privacy Policy
- Terms
- Resume Builder
- Blog
- Profile (requires login)
- Auth (sign-in and session)
Blog Posts
- Beyond Autocomplete: The Rise of CLI-First AI Coding Agents AI • By Shaik Noor
- What Is Loop Engineering? AI • By Shaik Noor
- A Complete 60-Day Roadmap to Become a Data Engineer with Python Data Engineering • By Shaik Noor
- What to Prepare for an Informatica Admin Interview (PowerCenter + IDMC) Data Engineering • By Shaik Noor
- Junior Data Engineer Skills Checklist Roadmaps • By Shaik Noor
- Part 1: SQL Skills You Need to Be a Data Engineer SQL • By Shaik Noor
- Full-Stack Go Template Open Source • By Shaik Noor
- Noruj Is Now Open Source Open Source • By Shaik Noor
- The Only SQL Skills You Need to Be a Data Engineer SQL • By Shaik Noor
- The Simple Guide: Learn Python for Data Engineering Python • By Shaik Noor
- 5 SQL Concepts That Will Change How You See Databases SQL • By Shaik Noor
Tutorials
Quizzes
- Transaction Isolation, Locking, and Concurrency Control
- JSONB Querying & GIN Indexes
- B-tree Indexes
- Scan Types
- Reading Query Plans
- Capstone Project: Multi-Dimensional Sales Leaderboard
- PERCENT_RANK and CUME_DIST
- NTILE
- RANK vs DENSE_RANK
- ROW_NUMBER
- Offset Functions
- Running Totals and Cumulative Aggregates
- Ordered Windows and Frame Clauses
- Partitioning Windows
- Intro to Window Functions
- CTEs vs Views vs Subqueries
- Writable CTEs
- Recursive CTEs
- Chaining Multiple CTEs
- Intro to CTEs
- View Security
- Materialized Views
- Querying System Catalogs
- Creating, Querying, and Dropping Views
- What is a View?
- SELF JOIN
- FULL OUTER JOIN & CROSS JOIN
- LEFT JOIN & RIGHT JOIN
- INNER JOIN
- How Joins Work Conceptually
- Derived Tables & Scalar Subqueries
- EXISTS vs IN
- Correlated Subqueries
- Subqueries in WHERE
- Introduction to Subqueries
- ORDER BY Deep Dive
- Why SELECT Aliases Fail in WHERE
- Execution Phases: SELECT to LIMIT
- Execution Phases: FROM to HAVING
- Order of Writing vs Order of Execution
- ROLLUP, CUBE, and Grouping Sets
- Filtering Groups with HAVING vs WHERE
- The GROUP BY Golden Rule
- Grouping by Computed Expressions
- Multi-column GROUP BY
- Grouping aggregates with GROUP BY
- PostgreSQL FILTER Clause
- Aggregates and NULL values
- COUNT Details
- Aggregate Functions
- Age Calculations and Timezones
- Truncating Dates
- Extracting Date Components
- Date Comparisons and Range Queries
- Date/Time Types & Intervals
- Handling NULL values
- Pattern Matching (LIKE, ILIKE, Regex)
- IN, NOT IN, and BETWEEN
- Combining Filters (AND, OR, NOT)
- WHERE Clause Basics
- DISTINCT & DISTINCT ON
- Type Casting & Basic String Manipulation
- Column Aliases
- Column Expressions & Arithmetic
- The SELECT Statement
- Setting Up PostgreSQL and Query Tools
- Reading Entity-Relationship (ER) Diagrams
- Keys & Relationships
- The Retail Data Model
- Relational Database Concepts
- SQL Window Functions: Analytics & Ranking Deep Dive
- SQL Constraints & Data Integrity Essentials
- JavaScript Core Mechanics: Scope, Promises, and Objects
- Docker Basics Mastery: Containers, Images & Commands
- SQL DDL: Creating & Structuring Database Tables
- SQL Data Modification: INSERT, UPDATE & DELETE Mastery
- SQL Conditions, Filtering & Sorting Fundamentals
- SQL Distinct, Limits & Basic Data Retrieval
- SQL Basics: Writing Your First Queries
- SQL Subqueries: Queries Within Queries
- SQL Joins: Combining Tables Like a Pro
- SQL Aggregations & Grouping: Core Concepts
- Python Basics – Variables, Data Types & Operations
- Retrieving Data
- SQL functions
SQL Practice Questions
- Total Revenue per Customer
- Count Orders per Day
- Top 2 Products by Revenue per Category
- Monthly Active Users (MAU)
- Customers with More Than 2 Orders
- Average Transaction Amount per Account
- First Order Date per Customer
- Orders Above Average Amount
- Customers Without Any Orders
- Most Recent Order per Customer
- Total Orders per Customer
- Identify Active Premium Subscribers
- Identify Low Stock Products
- Find High Priority Open Tickets
- Average Order Value by City
- Total Revenue by Product Category
- Employees with Salary Above Department Average
- Most Popular Post Category by Likes
- Courses With No Enrolled Students
- Top Earning Driver Per City
- Total Quantity Sold per Product
- Count of Employees per Department
- Most Followed Users on a Social Platform
- Total Spend per Customer This Year
- Filter 5-Star Reviews With Comments
- Identify Pending High-Value Transactions
- Find Overdue Unpaid Invoices
- Identify Abandoned Shopping Carts
- Hotels With Average Rating Above 4
- List Products Never Added to a Wishlist
- Most Logged-In Users This Month
- Month-over-Month Revenue Growth
- Employees Hired in the Last 90 Days
- Daily Revenue per Product
- Orders with Customer Names
- Total Likes per Post
- Active Users in the Last 7 Days
- Students Enrolled in More Than One Course
- Total Revenue per Salesperson
- Products with Zero Sales
- Count of Support Tickets by Status
- Average Session Duration per App
- Find Users Who Never Completed Their Profile
- Find Orders Placed on Weekends
- Top 3 Customers by Order Count Per Region
- List Active Customers
- Product Margin Math
- Unique Brand Offerings
- Catalog Pagination
- Postgres DISTINCT ON Demo
- High-Value Orders in 2023
- Premium Gmail Contacts
- Orders in Transition
- Quarterly Sales Window
- Retail KPI Dashboard
- Unique Product Catalog Coverage
- Sales by Store Type
- High-Status Customer Segments
- Computed Date Grouping
- Store Category Sales Matrix
- High-Performing Retail Outlets
- Dormant Customers
- Order Items Detailed Ledger
- Unstocked Retail Products
- Supervisor Reporting Chains
- Best-Selling Product Categories
- Product Performance View Audit
- Top Monthly Sales Months
- Top Customers Leaderboard
- Recursive Category Hierarchy
- Customer Running Ledger
- Month-over-Month Growth
- Customer Milestone Timestamps
- Top 3 Products by Category
- High-Tier Revenue Quartiles
- Product Feature Extraction
- Verified Review Sentiment
- Aggregate Products by Brand
- Writable CTE Salary Adjustment
- Upsert Store Inventory