If you haven’t learned it already although it’s not like Python or C++ learn T-SQL (transact SQL)well. I learned SQL and use MS SQL Server. Every job I have used SQL in that I have had as a programmer in the field.
SQL is a marketable skill and there are even SQL developer jobs. Even if you’re not a SQL Database Administrator SQL is tremendously useful because you will probably end up using some form if it in your programming jobs. I consider it a database programming language and it helps with your application development languages such as Python or C# very well although Python might use SQL with mysql instead of MS SQL Server.
Learning SQL is great and serves as a great foundation for a database programming language and helps with applications development and the backend.