SQL is a powerful language for managing and manipulating data within relational databases. One useful SQL function is LAST_VALUE, which allows us to retrieve the last value in a given column. In this blog post, we will explore how to use the LAST_VALUE function and how to combine it with the AS keyword for more meaningful results.

Syntax of the LAST_VALUE Function

The LAST_VALUE function is used to return the last value in a specified column. Here is the basic syntax:

LAST_VALUE(column_name) OVER (ORDER BY order_column ASC/DESC)

• column_name is the name of the column from which we want to retrieve the last value.
• order_column is the column used to determine the order of the data.

Example Usage

Consider the following orders table:

Now, let’s say we want to find the last order amount for each customer. We can use the LAST_VALUE function to achieve this:

SELECT DISTINCT
  customer,
  LAST_VALUE(amount) OVER (PARTITION BY customer ORDER BY order_id ASC) AS last_order_amount
FROM
  orders;

In the above example, we’re using the LAST_VALUE function along with the OVER clause to specify that the calculation should be performed partitioned by the customer column and ordered by the order_id column.

The result of the query will be:

Here, we see that the LAST_VALUE function returns the last order amount for each customer.

Conclusion

The LAST_VALUE function in SQL provides a convenient way to retrieve the last value in a given column. By combining it with the AS keyword, we can assign meaningful names to the calculated results. This allows for more readable and informative queries. So the next time you need to find the last value in a column, give the LAST_VALUE function a try!

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