What is the best way to learn SQL for PMs?

I have done my bachelors and have read databases during my degree. But I am not really good at them because there has been quite some time. I have been not using SQL and not writing queries. So would love to know how I can sort of brush up my skills and sort of learn basics of SQL is and joins and reading data from database so that I will be able to sort of query data during my day to day job as a product manager.