In almost every program that you write, you need to make decisions. For example, if it is the end of the fiscal year, bonuses must be distributed to the employees based on their salaries. In order to compute employee bonuses, a program needs to have a conditional control. In other words, it needs to employ a selection structure (you learned about selection structure in Chapter 1).
Conditional control allows you to control the flow of the execution of the program based on a condition. In programming terms, it means that the statements in the program are not executed sequentially. Rather, one group of statements or another will be executed depending on how the condition is evaluated.
In PL/SQL, there are three types of conditional control: IF, ELSIF, and CASE statements. In this chapter, you will explore two types of conditional control ”IF and ELSIF ”and how these types can be nested one inside of another. CASE statements are discussed in the next chapter.