In SQL, the LAST_VALUE function is used to get the last value in a group of rows, based on an ordering specified by the ORDER BY clause. Additionally, you can use an IF statement to conditionally perform certain actions based on a given condition.

Syntax of LAST_VALUE function:

The syntax for using the LAST_VALUE function is as follows:

LAST_VALUE(expression) OVER (PARTITION BY column ORDER BY column [ASC | DESC] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)

Usage of LAST_VALUE function with IF statement:

You can combine the LAST_VALUE function with an IF statement to perform conditional operations based on the value returned by LAST_VALUE.

Here is an example:

SELECT column1, column2, IF(LAST_VALUE(column1) = 'some condition', 'true', 'false') AS conditional_result
FROM your_table
ORDER BY column1

In this example, the LAST_VALUE function is used to get the last value of column1, and then an IF statement is used to check if the last value satisfies a specific condition. If the condition is true, the result will be ‘true’; otherwise, it will be ‘false’.

Example Scenario:

Let’s consider a scenario where you have a table named orders, which contains information about customer orders, including the order_id, customer_id, and order_status. You want to retrieve the last order of each customer and display whether the order is ‘complete’ or ‘pending’.

Here is an example query:

SELECT customer_id, LAST_VALUE(order_status) OVER (PARTITION BY customer_id ORDER BY order_id DESC) AS last_order_status,
       IF(LAST_VALUE(order_status) OVER (PARTITION BY customer_id ORDER BY order_id DESC) = 'complete', 'true', 'false') AS is_complete
FROM orders

In this query, the LAST_VALUE function is used to retrieve the last order_status for each customer_id. Then, an IF statement is used to check if the last order status is ‘complete’. If it is, the is_complete column will have a value of ‘true’; otherwise, it will have a value of ‘false’.

Conclusion:

By combining the LAST_VALUE function with an IF statement in SQL, you can effectively perform conditional operations based on the last value obtained from a group of rows. This can be useful in various scenarios where you need to handle the last value based on certain conditions.

#SQL #LAST_VALUE #IF