What is the CASE Statement in sql?

The CASE statement is a powerful tool in programming and data manipulation that evaluates a series of conditions and returns a value based on the first condition that is met. Think of it as similar to the concept of an if-then-else statement.

Here's an in-depth explanation of how the CASE statement works:

1. Condition Evaluation: The CASE statement systematically goes through a set of conditions specified by the programmer. It starts with the first condition and evaluates whether it is true or false.

2. Termination on True Condition: When a condition evaluates to true, the CASE statement immediately terminates its evaluation and yields the corresponding result associated with that true condition. This means that only the first true condition is considered, and the rest of the conditions are ignored.

3. Handling No True Conditions: In cases where none of the specified conditions is true, and if there is an ELSE clause provided, the CASE statement will produce the value specified in the ELSE clause. This is useful for providing a default value or outcome when none of the conditions match.

To illustrate this concept, let's consider an example using a table called "EmployeeDemographics":

• EmployeeDemographics Table: This table presumably contains information about employees, such as their ages.

Now, let's create a CASE statement for this scenario:

In this example, we've set up three conditions:

1. If the employee's age is greater than 30, the outcome is 'OLD'.
2. If the employee's age is between 22 and 30, the outcome is 'YOUNG'.
3. If none of the above conditions are met (ELSE), the default outcome is 'CHILD'.

This CASE statement will evaluate the age of each employee in the "EmployeeDemographics" table and return one of the specified outcomes based on the age range that matches the condition. If none of the conditions match, it will default to 'CHILD'.

In summary, the CASE statement is a versatile tool for making conditional decisions in SQL and other programming languages, allowing you to handle different scenarios and produce appropriate results based on specified conditions.

Credit:Background image source was Google.