Examine the structure of the PROMOTIONS table:
The management wants to see a report of unique promotion costs in each promotion category.
Which query would achieve the required result?
A.
SELECT DISTINCT promo_cost, promo_category FROM promotions;
B.
SELECT promo_category, DISTINCT promo_cost FROM promotions;
C.
SELECT DISTINCT promo_cost, DISTINCT promo_category FROM promotions;
D.
SELECT DISTINCT promo_category, promo_cost FROM promotions ORDER BY 1;
I think A is also correct, since the columns order doesn’t matter on DISTINCT statement (it will retrieve unique combinations for promo_category and promo_cost). And I don’t see why would be necessary the ORDER BY clause based on what was asked on the question. So, I think A and D.
A is wrong because, the results would be something like below
Promo_cost Promo_category
1000 A
2000 A
1000 B
2000 B
The answer is D