Databases & SQL
Most database trouble is a schema or an index decision made months earlier. These articles cover querying well, what an index actually does to a lookup, how transactions protect you, and the honest trade-offs between relational and document stores.
Querying
- Database Transactions: ACID, Isolation and Deadlocks Two UPDATE statements in a row are not a transaction. Catching the exception does not undo the first one, and that is how money disappears from a wallet table. Tutorial · 12 min read · August 6, 2026
- ORM vs Raw SQL: The N+1 Problem and When to Drop Down The loop that prints student.college.name runs one query per student. It is instant on your twenty-row dev database and it times out the moment real data arrives. Comparison · 12 min read · August 6, 2026
- SQL Injection Explained: The Fix Is Not Escaping Quotes Two dashes typed into a login box can delete the password check from your own query. The fix is not smarter escaping, and most beginners reach for escaping first. Tutorial · 12 min read · August 6, 2026
- SQL Commands Cheat Sheet for Interviews and Daily Work Every SQL command you need in one place, with the execution order that explains most of the errors beginners hit. Tips & Tricks · 10 min read · August 6, 2026
- SQL Interview Questions for Freshers (With Answers) SQL rounds are predictable. Joins, aggregation and one query about the second-highest salary account for most of what you will be asked. Career · 12 min read · August 6, 2026
- SQL Indexes Explained: When They Help and When They Hurt An index is the biggest single win available on a slow query — and the easiest thing to add so carelessly that it makes the database worse. Tutorial · 11 min read · August 5, 2026
- SQL Subqueries Explained: Queries Inside Queries Subqueries let you run a query inside another query. Learn how to use them in WHERE, FROM and SELECT — with clear examples, gotchas, and subquery vs JOIN. Tutorial · 8 min read · July 22, 2026
- SQL GROUP BY and HAVING Explained with Examples A beginner-friendly guide to SQL GROUP BY, aggregate functions, and how HAVING differs from WHERE, using a simple orders table and worked examples. Tutorial · 9 min read · July 22, 2026
- MongoDB Aggregation Pipeline Explained for Beginners A beginner-friendly guide to the MongoDB aggregation pipeline. Chain $match, $group, $sort, $project and $limit to find total orders per customer. Tutorial · 8 min read · July 22, 2026
- SQL Joins Explained: INNER, LEFT, RIGHT and FULL Learn how SQL JOINs combine rows from two tables. We cover INNER, LEFT, RIGHT and FULL OUTER JOIN with small examples, runnable queries and a cheat sheet. Tutorial · 9 min read · July 22, 2026
- SQL vs NoSQL: When to Use Which Database Relational or document? Compare schemas, scaling, transactions and query power, and learn the question that actually decides it for your project. Comparison · 10 min read · May 7, 2026
- SQL vs NoSQL: When to Use Which Database MySQL or MongoDB? PostgreSQL or Firebase? Understand the tradeoffs so you pick the right database for your project. Comparison · 10 min read · May 7, 2026
Design and performance
- MongoDB Schema Design: Embed or Reference? MongoDB will happily let one service store a pincode as a string and another store it as a number. Nothing errors. Your queries just quietly return half the results. Tutorial · 12 min read · August 6, 2026
- Redis Caching Basics: Cache-Aside, TTL and Invalidation A cached object comes back from Redis as JSON, so the Date you put in is now a string. The code that worked yesterday throws on line one, and only for cache hits. Tutorial · 12 min read · August 6, 2026
- MongoDB Indexes Explained: Faster Queries the Right Way Indexes are the single biggest win for MongoDB read speed. Here is how to create the right ones and prove they work with explain(). Tutorial · 9 min read · July 22, 2026
Beyond relational
- DBMS Interview Questions and Answers for Freshers DBMS theory rounds are predictable. Normalisation, ACID and keys account for most of what campus interviews ask. Career · 12 min read · August 6, 2026
- MongoDB CRUD Operations: A Beginner's Tutorial A hands-on beginner tutorial for MongoDB CRUD operations in the mongo shell — insert, find, update, and delete documents in a users collection. Tutorial · 9 min read · July 22, 2026
More on Databases & SQL
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- CSS Media Queries: Make Your Site Responsive A beginner-friendly guide to CSS media queries: mobile-first thinking, breakpoints, min-width vs max-width, and a before/after responsive card demo. Tutorial · 9 min read · July 22, 2026