3.2. Built-In Single-Row Functions
The previous sections covered all the basics of a SELECT statement using DUAL and how strings and numbers are constructed, compared, and combined. Now we can start looking at some of Oracle's built-in single-row functions that operate on strings and numbers in database table columns.
In both Oracle SQL and most programming languages, a function is a predefined set of steps that can be accessed using a common name. A function may include zero, one, or more arguments that are passed to the function, and it may return a result. For example, the SQRT function calculates the square root of a number and returns a value of 1.414214 when called with an argument of 2: SQRT(2) = 1.414214.
A named set of predefined ...