If you complete the intermediate level, you can advance to Hackerank SQL Level 4 (4 stars). I am an administrator who runs a verification center at a mobile phone subsidiary. This lecture gave me the opportunity to remind myself of SQL that I had forgotten. In addition, I plan to take the advanced level in the future and use it for SQL acceptance test verification. Thank you. See you in the advanced level~~~~. Ah, after taking this lecture, I got addicted to Hackerank and couldn't sleep, so I was tired the next day..ㅠ If you send me a cheatseat quickly, it would be a panacea~~! yunpha123@naver.com