How to use IF function in MySQL

The IF function in MySQL is a very commonly used function. Its function is to return different results according to given conditions. The IF function is usually used for conditional judgment and result return in query statements, and is often used as a replacement for IF-THEN-ELSE statements. The following will introduce the usage of the IF function in detail and provide some code examples.

First of all, the syntax of the IF function is as follows:

IF(condition, value_if_true, value_if_false)

Among them, condition is the condition to be judged. If the condition is true, return value_if_true; if the condition is not true, return value_if_false.

The following are some common usage scenarios and corresponding code examples:

1. Determine whether a field meets the conditions and return different results:

SELECT name, IF(age >= 18, 'Adult', 'Minor') AS age_group
FROM students;

In this example, if the student's age is greater than or equal to 18 years old, Then "Adult" is returned, otherwise "Minor" is returned.

2. Use the IF function for multi-condition judgment:

SELECT name, IF(score >= 90, 'Excellent', IF(score >= 80, ' Good', 'Pass')) AS grade
FROM students;

In this example, the grade is determined based on the student's score. If the score is greater than or equal to 90 points, "Excellent" is returned; if the score is greater than or equal to 80 points, "Good" is returned; otherwise, "Pass" is returned.

3. Use the IF function to convert fields:

SELECT name, IF(gender = 'M', 'Male', 'Female') AS gender
FROM students;

In this example, conversion is performed based on the student's gender field. If the gender is "M", return "Male"; otherwise, return "Female".

4. Use the IF function for conditional calculation:

SELECT name, IF(status = 'paid', amount, 0) AS payment
FROM orders;

In this example, the judgment is based on the status field of the order. If the order status is "paid", the order amount is returned; otherwise, 0 is returned.

It should be noted that the IF function can also be used with other functions, such as using the IF function for string splicing, date format conversion, etc.

To summarize, the IF function is a very commonly used function in MySQL, which can return different results according to given conditions. By flexibly using the IF function, we can make various conditional judgments and result returns to meet the needs of practical applications. I hope the above introduction and examples can help you understand and use the IF function.

The above is the detailed content of How to use IF function in MySQL. For more information, please follow other related articles on the PHP Chinese website!