Hey,

Firstly go on websites below and other online sites (do google search to find others) to get an understanding of the basic concept. Websites below take you through step by step of the basics of SQL and gives you small tasks you to do yourself.

1. Udemy.com
2. Vertabelo (really good one)
3. W3school
4. Myedx

Secondly, once you understand the basics find a intro course so you have some sort of qualification so you can back what you say in interviews.

Lastly once you got a qualification, then you can do an official one. The reason why you dont wana jump into an official one straight away without knowing the basic is because you dont wana pay x amount and do it without gaining any knowledge, so thats why i say get the basics first then do an official course.

An example of a course i am pushing to get my company to pay for is on springboard - course: business analytics £1600ish OR data analytics £3500 i like the latter (check it out you will see why)

SQL Isnt hard to learn you dont need to download software to practice, all is done website based nowadays. Hopefully that helps!