Spark SQL defines built-in functions to use, a complete list of which can be found [here](api/sql/). Among them, Spark SQL has several special categories of built-in functions: [Aggregate Functions](sql-ref-functions-builtin-aggregate.html) to operate on a group of rows, [Array Functions](sql-ref-functions-builtin-array.html) to operate on Array columns, and [Date and Time Functions](sql-ref-functions-builtin-date-time.html) to operate on Date and Time.