The **`CASE` statement** in MySQL is a conditional statement that goes through conditions one by one and returns the value provided for the first satisfying condition. 

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# Syntax

Given below is the syntax for the `CASE` statement:

- **`condition_1, ... condition_k`:** Conditions that need to be evaluated (in the same order in which they are listed).

- **`return_1, ..., return_k`:** Return values if the respective condition is satisfied. If no condition is satisfied, and there is no `ELSE` clause, `NULL` is returned.

> **Note**: A `CASE` statement must have at *least one* condition that returns a value. More than one conditions and even the `ELSE` clause is *optional*.

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# Example

Consider the following table, `Persons`. Given below is a query that demonstrates how to use the `CASE` statement:

The `CASE` statement given below *(Lines 2-7)* has three conditions that check whether the `Salary` of a person is *less than 1800*, *equal to 1800* or *more than 1800*. The returned string value is then printed out for each row along with the first and last name of that person *(Line 1).*

SELECT P.FirstName, P.LastName,
  CASE
    WHEN P.Salary < 1800   THEN 'Less Than 1800'
    WHEN P.Salary = 1800   THEN 'Equal To 1800'
    WHEN P.Salary > 1800      THEN 'More Than 1800'
    ELSE 'No Salary Data Found'
  END
FROM Persons P;

How to use the CASE statement in MySQL


The MySQL CASE statement evaluates conditions sequentially, returning the value of the first satisfied condition or NULL if none are met.