Oracle Database 10g SQL (Osborne ORACLE Press Series)

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.