SQL LAST_VALUE with CREATE statement

28 Sep 2023

In SQL, LAST_VALUE is a window function that returns the last value in an ordered set of rows. It can be useful when you want to retrieve the last value in a column or perform calculations based on the last value.

In this blog post, we’ll explore how to use the LAST_VALUE function with a CREATE statement to create a new table in SQL.

Syntax

The syntax for using LAST_VALUE with a CREATE statement is as follows:

CREATE TABLE new_table AS
SELECT column1, column2, LAST_VALUE(column3) OVER (ORDER BY column4) AS last_value_column
FROM existing_table;

Let’s break down the syntax:

CREATE TABLE new_table: This is the CREATE statement to create a new table named new_table.
AS SELECT: This specifies that the data for the new table will be selected from an existing table.
column1, column2: These are the columns from the existing table that you want to include in the new table.
LAST_VALUE(column3) OVER (ORDER BY column4) AS last_value_column: This is where the LAST_VALUE function is used. It retrieves the last value of column3 by ordering the rows based on column4.
FROM existing_table: This specifies the existing table from which to select the data.

Example

Let’s consider an example to understand how to use LAST_VALUE with a CREATE statement.

Suppose we have an existing table named sales with the following structure:

order_id	product_name	quantity	order_date
1	Product A	10	2022-01-01
2	Product B	5	2022-01-02
3	Product C	8	2022-01-03
4	Product D	12	2022-01-04

We want to create a new table named last_order that includes the order_id, product_name, and the last value of the quantity column, based on the ascending order of order_date.

The SQL code to achieve this would be:

CREATE TABLE last_order AS
SELECT order_id, product_name, LAST_VALUE(quantity) OVER (ORDER BY order_date) AS last_quantity
FROM sales;

After executing this code, the last_order table would be created with the following data:

order_id	product_name	last_quantity
1	Product A	12
2	Product B	12
3	Product C	12
4	Product D	12

As you can see, the last_quantity column in the last_order table contains the last value of the quantity column from the sales table.

Conclusion

Using the LAST_VALUE function with a CREATE statement allows you to create a new table in SQL, including the last value of a specific column from an existing table. This can be helpful when you need to preserve the last value or perform calculations based on it.