HackerRank’s SQL practice suite has hundreds of questions available for you to practice. You can filter the questions by their difficulty levels: easy, medium, and hard. If you are a Leetcode user, you can practice SQL on it too. LeetCode is quite diverse, with varying difficulty levels and topics.
Table of contents
1. HackerRank2. SQLPad3. StrataScratch4. DataLemur5. LeetCode6. Mode7. SQLZooConclusionSort: