You did well! All right, it's time to wrap things up. First, let's summarize what we've covered in this part:

1. A CASE WHEN statement checks for one or more conditions and returns a value when it finds the first matching condition. If there is no ELSE clause and no matching conditions, CASE WHEN returns NULL.

   CASE
     WHEN condition1 THEN result1
     WHEN condition2 THEN result2
     ...
     ELSE result
   END
   

2. To add a new column, and thus a custom classification of business products, you can use CASE WHEN in the SELECT clause:

   SELECT 
     CASE
       WHEN ... THEN ...
     END AS SampleColumn
   FROM Table;
   

3. You can use CASE WHEN in a GROUP BY clause to create your own grouping. The same CASE WHEN clause must also appear in the SELECT clause:

   SELECT 
     CASE
       WHEN ... THEN ...
     END AS SampleColumn,
     COUNT(*) AS SampleCount
   FROM Table
     ...
   GROUP BY
     CASE WHEN ... THEN ...
     END;
   

4. You can create a custom count of business objects using CASE WHEN inside a COUNT() or SUM() function:

   SELECT 
     COUNT(CASE
       WHEN ... THEN ColumnName
     END) AS CountColumn
   FROM Table;
   

   SELECT 
     SUM(CASE
       WHEN ... THEN 1
     END) AS CountColumn
   FROM Table;
   

How about a short quiz now?