Blog

9 posts: company guides, SQL and Python walkthroughs, system design, A/B testing, career advice.

🏢Companies0🗄SQL6🧪A/B testing & statistics1📊Product analytics0🐍Python0🎯Career & interviews2
🗄

SQL

6 posts
May 17, 2026

Account takeover detection in SQL

How to detect account takeover with SQL: new-device logins, email/password swaps, fresh cards, 2FA disable. Scoring, pitfalls, and FAQ for fraud analysts.

Read →
May 17, 2026

Actions per session in SQL

How to compute actions per session in SQL: meaningful interactions, action-type breakdowns, post-release dynamics, pitfalls, and FAQ from interviews.

Read →
🧪

A/B testing & statistics

1 post
May 15, 2026

A/B testing peeking — the mistake that fails 40% of junior PMs in interviews

Why looking at p-values every day inflates false positives to 30-40%, what the math says, and how senior PMs answer this in interviews.

Read →
🎯

Career & interviews

2 posts
May 17, 2026

Welcome to naildd — interview prep across tech roles

What naildd is, who it's for, and how we'll help you nail your next tech interview.

Read →
May 13, 2026

How to answer 'why are you leaving your job' in tech interviews

The behavioral interview question every tech candidate gets — what hiring managers are actually listening for and what to avoid.

Read →