SQL training can be free or can be very expensive, but the fact is if you are in IT you need it. Most software applications use one or another form of data storage, and the majority use RDBMS as an application backend.
There are many free SQL tutorial web sites which can teach you SQL, and they vary from basic instructions for SQL newbies to sites explaining advanced SQL concepts. Most of these sites are good for basic SQL training, and some of them are really well written and you can learn SQL on a decent level. When using a free SQL guides for SQL training, make sure that you practice the concepts that you learn, otherwise you will forget them quickly or will have problems using them down the road.
Another option for SQL training is to buy a good SQL book and learn from it. This is the cheapest paid option to learn and practice SQL. Most of the SQL books are big and they can be used for reference, so if you find a book recommended by a lot of readers just buy it.
If you don''t want to use a book or a free website in your SQL preparation, then you always have the option to pay for a SQL course. There are many companies offering 3-4 days courses which cost from 1K to several thousands, and if you have the money or if you company is willing to pay for the SQL training just go for it.
You don''t have to limit yourself to only one of the options above. It''s much better if you use more than one SQL training alternative, as they usually complement each other and you can always sharpen your SQL skills.