Here's a comprehensive list of free SQL resources which most of them I have practiced and attempted myself or are highly recommended for beginners regardless of whether you're from data or non-data background.
1. Alex Freberg
- Basic - https://lnkd.in/gEPqCqUh
- Intermediate - https://lnkd.in/g_sYJgw3
- Advanced - https://lnkd.in/gzt72UdA
- Programming with Mosh - 3-hour course - https://lnkd.in/gAiZwfQQ
- freeCodeCamp - 4-hour course - https://lnkd.in/gH9tYvsx
- Edureka - 4-hour tutorial - https://lnkd.in/gAwYniXM
- Kudvenkat - https://lnkd.in/gZSQbS-e
- Udacity SQL for Data Analysis - https://lnkd.in/gzsyYZs4
- Kaggle
- Intro to SQL - https://lnkd.in/gbGFuaKm
- Advanced SQL - https://lnkd.in/gpCrW74C
- Danny Ma's SQL Masterclass Course - https://lnkd.in/ge7zyWzu
- SQL Murder Mystery - https://lnkd.in/gmZvA-i8
- SQL Bolt - https://sqlbolt.com/
- Select Star SQL - https://selectstarsql.com/
- W3schools - https://lnkd.in/gXyQF3eU
- SQL Zoo - https://sqlzoo.net
- Covid-19 Project - https://lnkd.in/g8PqmFzb
- 8 Week SQL Challenges - https://lnkd.in/gjucZR6T. Check out my repo for solutions: https://lnkd.in/gkaNAibU
- StrataScratch - https://lnkd.in/gBTMYcmm
- LeetCode - https://lnkd.in/gXv63ebx
- HackerRank - https://lnkd.in/gAywRHs6