Beginner · About 50–65 minutes per day · 7 days
Learn SQL from YouTube in 7 days
SQL clicks when every day produces a query you can reuse at work. This week moves from SELECT to joins and simple aggregates using YouTube instructors who teach with real tables. You finish able to answer common business questions without waiting on an analyst.
Your 7-day program
Day 1 — How do you read a table and write a safe SELECT?
Inspect columns, select only what you need, and always limit rows while exploring.
Day 2 — How do you filter rows without breaking the logic?
Use WHERE with AND/OR carefully, handle NULLs, and compare strings and dates correctly.
Day 3 — How do you sort and page results for reports?
ORDER BY, LIMIT/OFFSET patterns, and when DISTINCT helps versus hides duplicates.
Day 4 — How do inner joins connect related tables?
Join customers to orders on keys, alias tables, and verify row counts before trusting totals.
Day 5 — When should you use left joins instead?
Keep unmatched rows, find missing relationships, and avoid accidental inner-join filters in WHERE.
Day 6 — How do aggregates answer business questions?
COUNT, SUM, AVG with GROUP BY, and HAVING to filter groups after aggregation.
Day 7 — How do you ship a reusable weekly metrics query?
Combine joins and aggregates into one readable query, comment assumptions, and save it for reuse.
Creators you will learn from
Estimated time: About 50–65 minutes per day · 7 days. Level: Beginner.
FAQ
Which SQL dialect do I need?
The week sticks to portable syntax that works in PostgreSQL, BigQuery, and most warehouse SQL with tiny tweaks.
Do I need a local database installed?
A free sandbox or sample dataset is enough. Challenges ask for queries and results, not a production setup.
I already know SELECT — can I start later?
Start on Day 4 if joins are the gap. The later days assume you can filter and sort confidently.
Will this cover window functions?
Not in depth. Week one locks core SELECT, joins, and aggregates so you can keep learning advanced topics next.