Because the condition in the if statement is false. This means that the block below the if statement is not executed. Output: You can use the IF statement to implement conditional branching logic in your programs. This allows you to implement requirements such as: This readability issue becomes even more important when you use the ELSE and ELSIF keywords and nest one IF statement into the other. Leverage indentation and formatting to make the logic of your IF statements easily decipherable. Future maintenance programmers will thank you. In this example, the IF statement determines whether sales are greater than the acquisition cost and updates the variables b_profitable accordingly. Nested IF statements are often necessary to implement complex logical rules, but you should use them carefully. Nested IF statements, such as nested loops, can be very difficult to understand and debug.

If you find that you need to nest more than three layers in your conditional logic, you need to look at that logic and see if there is an easier way to encode the same request. If not, you must create one or more local modules to hide the most internal IF statements. Although overlapping conditions are allowed in an IF-THEN ELSIF statement, it is best to avoid them if possible. In my example, the original specification is somewhat ambiguous when it comes to dealing with borderline cases like $20,000. Assuming the intention is to give the highest bonuses to the lowest paid employees (which seems to me to be a reasonable approach), I would abandon the BETWEEN operator and use the following logic below/above it. Note that I also gave up the ELSE clause just to illustrate that it is optional: it is the simplest form of the IF statement. The condition between IF and THEN determines whether the statement set should be executed between THEN and END IF. If the condition is rated to FALSE or NULL, the code will not run. You can use the IF-THEN-ELSIF statement to choose between several alternatives. An optional ELSIF. ELSE Statement. You can use the ELSIF clause to add additional conditions.

Now, whenever you need to test if the total number of a command exceeds the maximum, you can write the following IF statement, easy to understand: I found something interesting when I did some research on the short-circuit behavior of PL/SQL. The behavior you receive depends on the context of the expression. Consider the following statement: In this chapter, we have learned about the various decision-making statements, their syntax, and examples. The following table contains a summary of the various conditional instructions we discussed. Oracle provides the following types of decision-making instructions. Note these points about the syntax of the IF statement: If one condition is true, the following other conditions are not evaluated. If no conditions are true, the else_statements between ELSE and ENDIF is executed. If you ignore the ELSE clause and no condition is TRUE, then THE IF THEN ELSIF does nothing The latter and the most complex form of the IF statement selects a true condition from a set of mutually exclusive conditions, and then executes all the statements associated with that condition. If you are writing IF statements like this with a version that begins with Oracle9i Database Release 1, consider using case statements that you are looking for instead.

It is important to remember that one of the two sequences of instructions is always executed because IF-THEN-ELSE is a gold-or construction. After the appropriate set of statements is executed, the control is passed to the statement immediately after the END IF keyword. There are real situations where we have to make decisions, and based on those decisions, we decide what to do next. Similar situations also occur in programming, where we have to make decisions and execute the next block of code based on those decisions. I want to merge the condition results of my 2 If statements. First, if the result of the statement displays only 0 results, in the second, if the result of the statement of one of them must be greater than 0. If you type ELSEIF instead of ELSIF, the compiler is also confused and does not recognize ELSEIF as part of the IF statement. Instead, the compiler interprets ELSEIF as a variable or procedure name. In this example, employees whose salary is greater than $40,000 receive a bonus of $500, while all other employees receive no bonus. Or is it? What happens if, for some reason, a particular employee`s salary is ZERO? In this case, the statements are executed in accordance with the ELSE and the employee in question receives the bonus, which should only go to high-paid employees. It`s not good (well, it was good in the last section, but not now)! If the content can be NULL, you can use the NVL function to protect yourself from this problem: unlike an IF statement, condition1 does not short-circuit this expression if condition1 is null. Why not? Because the result can be NULL or FALSE, depending on condition2.

For an IF statement, NULL and FALSE both lead to the ELSE branch, so a short circuit can occur. However, for an assignment, the final value must be known, and a short circuit can (and will) occur in this case only if condition1 is FALSE. Logically, the IF-THEN-ELSIF construct is a way to implement the case statement functionality in PL/SQL. If you`re using Oracle9i Database and oracle9i, it`s probably best to use a CASE statement (which is discussed later in this chapter). The keywords THEN, ELSE, and ELSIF must not have a semicolon after them. These are not stand-alone executable statements and, unlike END IF, they do not complete an instruction. When you insert a semicolon after these keywords, the compiler sends messages indicating that it is looking for a statement before the semicolon. When using IF-THEN-ELSIF statements, there are a few things to consider. The latter form of the IF statement is useful when you need to implement logic that provides many alternatives. it is not a situation of one or the other.

The IF-ELSIF formulation allows you to handle multiple conditions in a single IF statement. In general, you should use ELSIF with mutually exclusive alternatives (that is, only one condition can be TRUE for each execution of the IF statement). The general format of this variation of the IF is as follows: A major advantage of the interlocking IF structure is that it modifies the assessment of internal conditions. The conditions of an internal IF statement are evaluated only if the condition of the external IF statement that includes it is evaluated at TRUE. Therefore, an obvious reason to nest IF statements is to evaluate a condition only if another condition is TRUE. For example, in my bonus allocation code, I could write the following: In this example, we print the largest of the three numbers using the Nested-If statement. The numbers are assigned in the declaration part, as you can see in the following code, i.e. Number = 10, 15 and 20, and the maximum number is retrieved with the nested if statements. The conditions of the IF-ELSIF are always evaluated in order from the first condition to the last condition. If two conditions are evaluated to true, the statements in the first condition of that type are executed.

Under the current example, a salary of $20,000 translates into a bonus of $1,500, although this salary of $20,000 also fulfills the condition of a bonus of $1,000 (ENTRE is included). Once a condition is evaluated at TRUE, the remaining conditions are not evaluated at all. The block of code that follows the else statement is executed as a condition that exists in the if statement is false after the statement that is not contained in block (without spaces) is called. This is reasonable because I want to print a message for every bonus check issued, but I don`t want to print a bonus check for a zero amount if no bonus has been granted. .