SQL Interview Core
Group by, joins, windows, retention, funnels, ranking, and business metrics.
Open SQL setsDATA
practice like the interview is real
Digits
n Data
A high-signal practice hub for data aspirants becoming data professionals, and for working data professionals sharpening SQL, analytics, statistics, product sense, and interview execution.
90
SQL questions live
9
company-style sets
5
career tracks
1
daily practice loop
build the stack
Practice paths for data careers
Analytics Thinking
Turn raw tables into decisions: define metrics, spot tradeoffs, and explain results.
See methodStatistics Muscle
Distributions, experiments, confidence, bias, variance, and practical A/B testing.
Train nextProduct Data Sense
Frame ambiguous business questions and choose metrics that survive scrutiny.
Practice framingProfessional Upskill
Keep your edge with harder prompts, cleaner communication, and interview-ready reps.
Upskill plan
company practice
SQL sets inspired by real data work
Pick a company, open question one, and move through the set like a focused interview sprint.
UPSKILL
from practice to profession
Become the person who can answer the question and explain why it matters.
The loop is simple: solve, compare, explain, repeat. Beginners build interview fluency. Professionals sharpen the judgment that makes analysis useful in meetings, dashboards, experiments, and product decisions.
01Read the business question
02Find the grain of the data
03Write the query cleanly
04Explain the decision impact
data disciplines to keep in motion