Real SQL for real analyst work
Dirty data, career context, and the things bootcamps skip. Long-form guides with free exercises you can run against a realistic star schema.
- Data Quality10 min read
The SQL Data-Quality Checks Senior Analysts Run Before Every Report
The 30-second sweep that catches 80% of "why does this number look weird" bugs before they reach a stakeholder — NULL audits, dedup checks, refund leakage, timezone sanity.
Read the post - Technique11 min read
Cohort Retention in SQL: The Query Every Analyst Eventually Owns
The retention triangle is the single most-requested chart in product analytics. Here’s how it’s built — cohort anchor, grid query, NULL traps, and how to read what stakeholders actually ask for.
Read the post - Finance12 min read
Vintage Curves, Roll Rates, and the SQL Credit-Risk Analysts Write
The two queries every credit-risk analyst owns by year two — how to build them from scratch in SQL, why banks care, and how they show up in an interview.
Read the post - Technique10 min read
CASE WHEN for Business Logic: The Pattern Analysts Underrate
The one SQL construct that turns vague stakeholder asks into queryable rules — with the NULL traps and pivot patterns that decide senior-analyst code from junior-analyst code.
Read the post - Technique12 min read
The Seven SQL Patterns That Cover 80% of Data Analyst Interviews
Every FAANG SQL screen draws from the same seven patterns. This is the primer — the verbatim questions, the canonical solutions, and the trap variants that separate strong candidates.
Read the post - Data Quality8 min read
How to Diagnose a Dashboard That Looks Wrong
A senior analyst’s triage playbook for the Monday morning Slack: "the number on the dashboard doesn’t match Finance — can you check?"
Read the post - Data Quality7 min read
Anti-Joins and the LEFT JOIN ... IS NULL Pattern
Finding what’s missing — the single most-used and most-often-written-wrong pattern in analyst SQL.
Read the post - Healthcare10 min read
SQL for Healthcare Analysts: The Queries That Matter
HEDIS measures, 30-day readmission logic, claims-vs-clinical reconciliation, and the PHI handling rules that will get you fired if you skip them.
Read the post - Career9 min read
Negotiating Your First Data Analyst Offer
Comp bands, signals that create leverage, and the three-message counter-offer script that works even when you don’t have a competing offer.
Read the post - Data Quality12 min read
Donor Deduplication in SQL: A Practical Playbook
A field-tested SQL playbook for finding duplicate donor records — exact match, normalized match, phonetic codes, Levenshtein, and composite scoring — with the gotchas nonprofits actually hit.
Read the post - Career9 min read
From Data Analyst to Analytics Engineer: The Career Step
The dbt-shaped role that sits between analyst and data engineer — who it’s the right next step for, what skills you actually need, and how to position for the jump.
Read the post - Career Change8 min read
Building an Analyst Portfolio That Gets Interviews
Three projects, one repo, one shareable writeup — the portfolio shape that actually converts cold applications into phone screens.
Read the post - Technique9 min read
SQL Window Functions in Real Analyst Work
Running totals, top-N per group, month-over-month growth — the three window-function patterns that cover 90% of analyst work, with exercises.
Read the post - Technique9 min read
CTEs and Recursive Queries for Analysts
Why `WITH` changed how analysts write SQL, when to chain vs nest, and the one recursive pattern that every analyst will eventually need (org charts, category trees, session chains).
Read the post - Data Quality10 min read
How to Read a Messy Database Like a Senior Analyst
Every production database is a crime scene. Here’s the senior-analyst workflow for reading it: what to profile, what to distrust, and how to sanity-check before you report a number.
Read the post - Marketing10 min read
Attribution Models in SQL: Last-Touch, First-Touch, Linear, and the Rest
How marketing attribution actually gets computed — the five models analysts run against real event data, the trade-offs, and the SQL that makes each one defensible.
Read the post - Technique9 min read
SQL Performance for Analysts (Without Becoming a DBA)
The five query-performance moves that matter for analysts — indexes, EXPLAIN, materialization, and when a "slow" query is actually a grain bug in disguise.
Read the post - Career Change8 min read
SQL for Career Changers: No CS Degree Required
A 90-day plan for moving into a data analyst role from an unrelated field — with the portfolio moves, interview realities, and a first SQL exercise.
Read the post - Technique9 min read
SQL Joins for Analysts: A Practical Guide (with the Mistakes)
The five joins, when each is the right answer, and the three join mistakes that silently break production dashboards.
Read the post - Career8 min read
Why SQL Learners Fail at Real Jobs (And How to Fix It)
Tutorial SQL and job SQL look identical on paper and feel nothing alike in practice. Here’s the gap, and a concrete plan to close it.
Read the post - Marketing9 min read
SQL for Marketing Analysts: The Complete Guide
The queries, schemas, and mental models marketing analysts use every week — with exercises against a realistic campaign database.
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