Introduction to "else if" in MySQL

In MySQL, the "else if" statement is commonly used to implement conditional logic. It allows you to evaluate multiple conditions and execute different blocks of code based on the results. The "else if" statement is also known as the "elseif" statement in MySQL.

Syntax

The syntax for the "else if" statement in MySQL is as follows:

IF condition1 THEN
    -- code block 1
ELSEIF condition2 THEN
    -- code block 2
ELSEIF condition3 THEN
    -- code block 3
...
ELSE
    -- code block executed when none of the conditions are true
END IF;

Explanation

• The "condition1" is a boolean expression that evaluates to either true or false. If it is true, then the code block 1 will be executed.
• If condition1 is false, then MySQL moves to the next "elseif" statement (condition2) and evaluates it. If condition2 is true, code block 2 will be executed.
• This process continues until either one of the conditions is true, or all conditions have been evaluated without any true result.
• If none of the conditions are true, the code block within the "else" statement will be executed.

Example

Let's consider an example where we want to check the grade of a student based on their score:

SET @score = 85;

IF @score >= 90 THEN
    SET @grade = 'A';
ELSEIF @score >= 80 THEN
    SET @grade = 'B';
ELSEIF @score >= 70 THEN
    SET @grade = 'C';
ELSEIF @score >= 60 THEN
    SET @grade = 'D';
ELSE
    SET @grade = 'F';
END IF;

SELECT @grade;

In this example, the score is set to 85. The code uses the "else if" statements to check the score against different ranges and assigns a grade accordingly. In this case, the score falls between 80 and 89, so the grade will be 'B'. The final SELECT statement displays the grade.

Note that in this example, we used user-defined variables (@score and @grade), but in an actual MySQL application, you might use table columns or stored procedure parameters.

Conclusion

The "else if" statement in MySQL allows programmers to implement complex conditional logic. It enables you to evaluate multiple conditions and execute different code blocks based on the results. Understanding the syntax and usage of "else if" statements is crucial for writing efficient and flexible MySQL programs.