In SQL, the LAST_VALUE function is used to retrieve the last value of an expression within a specified window frame. It is often used in combination with mathematical functions to perform calculations on the last value in a set of rows.

Let’s explore how to use the LAST_VALUE function with mathematical functions in SQL.

Syntax

The syntax for using LAST_VALUE with mathematical functions is as follows:

LAST_VALUE(expression) OVER (PARTITION BY column ORDER BY column [ROWS frame_spec])

• expression represents the column or expression on which the mathematical function will be performed.
• PARTITION BY is an optional clause that divides the rows into partitions based on a column.
• ORDER BY specifies the column used for ordering the rows within each partition.
• ROWS frame_spec defines the range of rows over which the mathematical function will be evaluated.

Example

Let’s consider a table called sales with the following structure:

Suppose we want to calculate the total sales amount for each product, using the LAST_VALUE function with the quantity and price columns.

SELECT product, LAST_VALUE(quantity * price) OVER (PARTITION BY product ORDER BY id) AS total_sales
FROM sales;

The above query will give us the following result:

In this example, the LAST_VALUE function calculates the product of quantity and price for each row, ordered by the id column. The result is then displayed for each product, giving us the total sales amount for each product considering the last value within each partition.

By using the LAST_VALUE function in combination with mathematical functions, we can perform calculations on the last value within a specified window frame, enabling more advanced data analysis in SQL queries.

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