I built a free, interactive SQL practice tool for data engineering interviews
Most data engineering interview prep resources I found online were static — a list of questions with answers underneath. You read the answer, nod, a…
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LuaDB – A pure Lua RDBMS engine with B+Trees, WAL, and Postgres wire protocol
I built LuaDB – an embeddable relational database written 100% from scratch in pure Lua (no C extensions or external dependencies). Key features: Sl…
What Has To Be True Before You Trust An AI Data Agent
An AI data agent turns a plain English question into a query, runs it, and hands back an answer. The demo is always impressive. The part that decide…
Performance Engineering: What Is the System Waiting For?
When a request takes five seconds, the obvious question is what to make faster. The more useful question is what, precisely, the system spent those…
Stop writing raw SQL in your migrations (most of the time)
Something I keep seeing across teams, especially with people who are getting comfortable with tools like db-migrate or Kysely , is a very specific h…
Prisma vs Drizzle vs Raw SQL: What Every Backend Developer Should Understand Before Choosing an ORM
When most developers start building backend applications, they're usually focused on one thing, getting an API working. Express routes, controllers,…
SQL Execution Order Internals: Why WHERE Fails on Aliases but ORDER BY Succeeds
Ever wondered why this query fails in SQL? SELECT department_id , COUNT ( * ) AS emp_count FROM employees WHERE emp_count > 5 -- ❌ Error: Invalid…
An ERD MCP Server: AI Agents That Follow Your Naming Standard
AI agents already write database schemas. Ask Claude or Cursor for a feature and the migration file comes back with tables, columns, and foreign key…
Postgresso 7-8 (92-93)
PGW: A PGBACKREST INTERLUDE: (Andreas Scherbaum, Jimmy Angelakos) Andreas Scherbaum and Jimmy Angelakos presented a quantitative analysi…
From Plain English to a Live Dashboard: Automating Reporting with MCP
Someone in your Slack asks, "How many people signed up last week?" You open a SQL client, write a query you've written a dozen times before, run it,…
How to Export SQL Results to CSV and Excel (Without Wrecking the Data)
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you will export a query result and open it with the leading zero…
SQLazy: Search for Adjacent Records at a Specified Offset Within Groups
Problem Description In a table, ProductionLine_Number is the grouping field, and within each group records are sorted by date_Time. The task is to s…
MCP vs. a Direct Database Connection: A Security and Workflow Comparison
Sooner or later, someone on your team wants to point an AI assistant at the production database. Maybe it's a support engineer who wants to answer "…
Web Performance on a Budget: Bundle Size, API Limits, and Database Indexes
The three budgets every web app hits: bundle size, API rate limits, and database index selectivity. Learn the formulas, thresholds, and PR checklist…
Prove Your Backups Actually Restore Automatically, on a Separate Server
If you haven't done any restoration of your backups, you cannot count it as your retrieval strategy. It's simply a case of gambling. The backup job…
PostgreSQL psql: Schema Navigation Quick Reference
A short refresher for navigating PostgreSQL databases, schemas, and objects from the psql command line. Schemas List all schemas: \ dn List schemas…
Bringing Relational SQL Databases to the P2P World
Have you ever wanted to integrate full-text search (or to be more trendy, vector similarity search) in to your P2P project only to be disappointed b…
A SQL interview is a translation test, not a syntax test
Canonical: this is a cross-post. The original lives at https://four-leaf.ai/blog/sql-interview-guide Key takeaways A SQL interview is a translation…
Which SQL Database Should You Install?
By Michael Nocito , data analyst · Published August 7, 2026 If you want to write SQL against your own data today, install a file-based engine: SQLit…
NULL in SQL: Why = NULL Finds Nothing and What to Write Instead
By Michael Nocito , data analyst · Published August 7, 2026 By the end of this page you can predict what any query does when it meets a missing valu…
Month-over-Month Growth in SQL: LAG, the Growth Formula, and the Traps
By Michael Nocito , data analyst · Published August 7, 2026 By the end of this page you can write a month-over-month growth query and trust its answ…
How to Find Duplicate Rows in SQL (and Decide What Counts as One)
By Michael Nocito , data analyst · Published August 7, 2026 By the end of this page you can check any table for duplicate rows, list every copy, and…
SQL Comment Syntax by Database: MySQL, PostgreSQL, SQL Server, SQLite, Oracle
By Michael Nocito , data analyst · Published August 11, 2026 Two comment forms are part of the SQL language itself and work in every database you ar…
COMMENT ON TABLE: How to Store a Table Description in the Database Itself
By Michael Nocito , data analyst · Published August 11, 2026 There are two completely different things in SQL called a comment, and searching for on…
How to Comment in SQL: -- and /* */, and the Two Traps That Break a Query
By Michael Nocito , data analyst · Updated August 11, 2026 SQL has two comment syntaxes and you will use both today. -- hides the rest of one line.…
Why I Stopped Rushing to Machine Learning and Started with SQL Instead!
I've solved 15 of the 50 problems in LeetCode's SQL 50. I started my first end to end ML project predicting telco customer churn this week. And thre…
Oracle Designer Lost Support in 2013. My AI Agent Develops in It Anyway.
Oracle Designer 10g is a CASE tool from the early 2000s. Support ended in 2013. At my job it is still the center of development: the repository hold…
That's why we should be focus on reviewing AI responce
Testing AI-Generated SQL With 10 Real-World Queries Gia Gia Gia Follow Aug 21 Testing AI-Generated SQL With 10 Real-World Queries # ai # database #…
MariaDB 10.6 to 13.0 for WordPress: Only One Upgrade Actually Does Anything [Benchmark]
Originally published on https://makewpfast.com/mariadb-versions-wordpress-benchmark/ Someone read my March post about MariaDB 10.11 vs 11.4 and aske…
Column Comments in PostgreSQL and MySQL: How to Document Columns Without a Migration
Disclosure: I build Schemity , a desktop ERD tool - this post is from our blog and uses it for the examples. TL;DR: The database has a built-in plac…