Generally, computer programs are written because certain tasks must be executed a number of times. For example, many companies need to process transactions on a monthly basis. A program allows the completion of this task by being executed at the end of each month.
Similarly, programs incorporate instructions that need to be executed repeatedly. For example, a program may need to write a number of records to a table. By using a loop, the program is able to write the desired number of records to a table. In other words, loops are programming facilities that allow a set of instructions to be executed repeatedly.
In PL/SQL, there are four types of loops: simple loops, WHILE loops, numeric FOR loops, and cursor FOR loops. In this chapter, you will explore simple loops, WHILE loops, numeric FOR loops, and nested loops. Cursor FOR loops are discussed later in the book.