In SQL, the LAST_VALUE function is used to fetch the last value in a specific window frame. It is commonly used in conjunction with the IS NOT NULL operator to filter out any NULL values.

Here’s an example of how you can use the LAST_VALUE function with the IS NOT NULL operator:

SELECT 
    column1,
    LAST_VALUE(column2) OVER (ORDER BY column3 ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS last_value_column
FROM 
    table_name
WHERE 
    column2 IS NOT NULL;

In the above example:

• column1 is the column you want to select in the result set.
• column2 is the column from which you want to fetch the last value.
• column3 is the column used for ordering the result set.
• table_name is the name of the table you are querying.

The ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING clause ensures that the window frame for the LAST_VALUE function encompasses all rows in the table.

The WHERE clause column2 IS NOT NULL filters out any rows where column2 has a NULL value.

By combining the LAST_VALUE function with the IS NOT NULL operator and proper window framing, you can retrieve the last non-NULL value from a specific column in your SQL query. This can be useful when analyzing time series data or retrieving the most recent value in a dataset.

#SQL #LAST_VALUE #IS_NOT_NULL