SQL is the most useful language to interact with Databases. The database structure is slowly changing.
History of Databases:
- Object oriented DBMS
- No SQL or New SQL
Each and every area you need to use SQL. Learning and mastering SQL is an asset in 21st century.
Having knowledge and updating latest databases give you job opportunities. I am learning CASANDRA, Mongo DB etc.
Here is SQL QUIZ link. It is completely free.