Question

I don’t understand the purpose of using syntax code “CASE GROUPING”?

Unfortunately, I don’t have the database to review the sourcecode below.

SELECT 
    CASE GROUPING(st.stor_name) WHEN 0 THEN st.stor_name ELSE 'ALL' END AS Store, 
    CASE GROUPING(s.type) WHEN 0 THEN s.type ELSE 'ALL TYPES' END AS Type, 
    SUM(s.qty) AS TotalSold 
FROM 
   (SELECT DISTINCT st.stor_id, t.type, 0 AS qty 
    FROM stores st CROSS JOIN titles t 
    UNION ALL 
    SELECT 
        s.stor_id, 
        t.type, s.qty 
    FROM sales s JOIN titles t ON s.title_id=t.title_id) s 
JOIN stores st ON (s.stor_id=st.stor_id) 
GROUP BY st.stor_name, s.type WITH CUBE 

Answer 1

CASE is a conditional expression, like an if statement.

GROUPING is a function that:

Indicates whether a specified column expression in a GROUP BY list is aggregated or not. GROUPING returns 1 for aggregated or 0 for not aggregated in the result set. GROUPING can be used only in the SELECT list, HAVING, and ORDER BY clauses when GROUP BY is specified.