Example: top-N per group (common Mosh exercise)
WITH ranked AS (
SELECT user_id, score,
ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY score DESC) rn
FROM scores
)
SELECT * FROM ranked WHERE rn <= 3;
Once you have unzipped and imported the course files, focus on these top SQL practices from Mosh’s advanced modules: programming with mosh sql zip file top
The ZIP file you download after purchasing The Complete SQL Mastery course contains: Example: top-N per group (common Mosh exercise) WITH
No external dependencies, malware, or bloatware – it’s clean. Once you have unzipped and imported the course
| You should get it if… | You might skip it if… | |----------------------|------------------------| | You learn best by doing | You already have your own large dataset | | You want to focus 100% on writing SQL, not building tables | You prefer cloud databases (AWS RDS, Supabase) | | You’re following Mosh’s video course | You hate installing local MySQL |
Even top programmers hit snags. Here’s a troubleshooting table:
| Error Message | Likely Cause | Solution |
|---------------|--------------|----------|
| ERROR 1064 (42000) | SQL syntax mismatch (Mosh’s MySQL vs your PostgreSQL) | Use the same DBMS as the course |
| zip file is corrupted | Incomplete download | Re-download from official source |
| Access denied for user | Wrong MySQL credentials | Reset root password or create new user |
| Unknown database 'mosh_db' | The script expects a DB that doesn’t exist | Add CREATE DATABASE IF NOT EXISTS at top of .sql file |
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