In this chapter, you learned that
The Oracle database has two main groups of functions: single row functions and aggregate functions.
Single row functions operate on one row at a time and return one row of output for each input row. There are five main types of single row functions: character functions, numeric functions, conversion functions, date functions, and regular expression functions.
Aggregate functions operate on multiple rows at the same time and return one row of output.
Blocks of rows may be grouped together using the GROUP BY clause.
Groups of rows may be filtered using the HAVING clause.
In the next chapter, you ll learn about dates and times.