Consider a table with two columns. The first, ID, is an incrementing integer,

the primary key of the table. The second column contains data values. Some

data values may be NULL. Here is the script that creates the temp table with

data values.

-- Create the table

CREATE TABLE #TableValues(ID INT, Data INT);

-- Populate the table

INSERT INTO #TableValues(ID, Data)

VALUES(1,100),(2,100),(3,NULL),

(4,NULL),(5,600),(6,NULL),

(7,500),(8,1000),(9,1300),

(10,1200),(11,NULL);

-- Display the results

SELECT * FROM #TableValues;

The exercise is to use window functions to replace each NULL value with the

previous non-NULL value.