nested case statement in sql

Nested CASE statements in SQL provide a powerful way to implement complex decision-making logic within a single query. Imagine a scenario where you need to categorize customer orders based on multiple criteria, such as order value and payment method. A single CASE statement can handle the initial categorization, and then a nested CASE statement can further refine the categorization based on additional conditions. This approach avoids the need for multiple separate CASE statements, making the query more concise and readable. Nested CASE statements are particularly useful when you need to apply a series of rules, where each rule depends on the outcome of the previous one. This hierarchical structure allows for a more nuanced and accurate categorization or decision-making process. For instance, you might first categorize orders based on their total value, and then further categorize them based on the payment method within each value category. This approach is more efficient than using multiple separate CASE statements, as it avoids redundant code and improves readability.