In SQL, the LAST_VALUE function is used to retrieve the last value in a group of rows. However, by default, it includes NULL values in the calculation. If you want to ignore NULL values and retrieve the last non-null value, you can make use of the IGNORE NULLS option in SQL.

Here’s an example to illustrate how to use the LAST_VALUE function with IGNORE NULLS:

SELECT 
    product_id,
    quantity,
    LAST_VALUE(quantity IGNORE NULLS) OVER (PARTITION BY product_id ORDER BY order_date) AS last_quantity
FROM
    orders;

In the above example, we have a table called orders with columns product_id, quantity, and order_date. We want to retrieve the last non-null quantity value for each product_id.

The LAST_VALUE function is used with the IGNORE NULLS option inside the OVER clause. The PARTITION BY clause is used to define the groups based on the product_id column. The ORDER BY clause is used to specify the order of the rows within each group.

By using the LAST_VALUE(quantity IGNORE NULLS), the function will return the last non-null quantity value for each group of product_id.

Conclusion

The LAST_VALUE function in SQL is a powerful tool for retrieving the last value in a group of rows. By using the IGNORE NULLS option, you can exclude NULL values and retrieve the last non-null value instead. This can be particularly useful when working with datasets that contain missing or null values.

#SQL #LastValue #IgnoreNulls