In this blog post, we will explore how to use the LAST_VALUE function in SQL along with the DROP statement to efficiently retrieve the last value in a sequence and remove it from the table.

What is LAST_VALUE Function?

The LAST_VALUE function is a window function in SQL that returns the last value in a sorted sequence. It is useful when you want to find the most recent or latest value in a group of rows.

Using LAST_VALUE with DROP Statement

Suppose we have a table called my_table with the following schema:

CREATE TABLE my_table (
  id INT,
  value VARCHAR(50)
);

We can use the LAST_VALUE function along with the DROP statement to retrieve and remove the last value from the value column. Here’s an example query:

WITH last_row AS (
  SELECT
    value,
    LAST_VALUE(value) OVER (ORDER BY id ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS last_value
  FROM
    my_table
)
DELETE FROM my_table
WHERE
  value = (SELECT last_value FROM last_row)

In the above query, we first create a CTE (Common Table Expression) named last_row which uses the LAST_VALUE function to select the last value from the value column and assigns it as last_value. The ROW BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING clause ensures that the window range includes all rows.

We then use a delete statement to remove the row(s) from my_table where the value column matches the last_value selected from the CTE.

Conclusion

In this blog post, we explored how to use the LAST_VALUE function in SQL along with the DROP statement to efficiently retrieve the last value in a sequence and remove it from the table. This can be useful in scenarios where you need to process the latest value and remove it from the dataset.