We believe strongly that daily users of RDBMS and SQL will greatly benefit by understanding the basics of discrete math and set theory that serve as the foundation for SQL.
You don't need a math degree to write and read SQL code, but the knowledge of how binary and hexadecimal numbers are different from decimals and how they can be converted to each other can help you to better understand issues directly related to it. Such issues include security issues, data encryption, data storage principles, and the Oracle ROWID data type — to mention just a few.
Understanding set theory is even more important. Basically, the result of any database query is a set of values, so it would benefit you immediately to know the rules of working with sets to create efficient queries.