There are upper division DSC courses which go into far more detail about using SQL and relational databases, particularly DSC 100. The resources linked below are meant for supplemental self-directed learning, practicing working with SQL, and for any non-DSC majors looking to learn more about this programming language outside a formal course.
What is SQL?
SQL (short for 'structured query language') is a programming language used for working with relational databases.
Amazon Web Services has a good summary of the value of SQL:
"Structured query language (SQL) is a programming language for storing and processing information in a relational database. A relational database stores information in tabular form, with rows and columns representing different data attributes and the various relationships between the data values. You can use SQL statements to store, update, remove, search, and retrieve information from the database. You can also use SQL to maintain and optimize database performance."